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Double D
07-02-2010, 10:35 AM
Needs some help guys. I will try to make this short and precise so you don't lose track.

Equipment:
1994 ProStar 205
350 CI Indmar, 275 HP
Throttle Body Fuel Injection

History:
July 2009 filled up with gas at Marina. Started running rough at idle so I thought I got bad gas.

My Fixes:
- Put in treatment in Gas.
- Ran tank empty
- Changed Gas/Water Separator
- Changed Thermostat
- Changed Plugs
- Changed Fuel Filter
- Tested Plug Wires

Result:
Still runs very rough at low idle. Stumbles when engaging to forward.

Next Step:
Took it to the local dealer where they did the following:
- Compression Tested the engine.
- Change Rotor and Cap
- Re-gapped the Plugs
- Replaced the timing control module
- Increased idle a bit
- Water tested it and said it was ready.

Result:
It started better and for the first 25 minutes of speeding and no wake it ran fine. We stopped to gear up to ski and the idle began surging, or should I say dropping. The range of idle on the RPM dial would be from 9 to 8, 9 to 8, 9 to 8 and it wouldn't stop. If you tried to put it in gear, half the time it would stall. So now it is running worse!

Next Step:
Returned it to the dealer where they did the following:
- Replaced two carburetor gaskets that were cracked and sucking air.
- replaced a clear yellow rubber vacuum hose for the map sensor
- Changed PVC Valve
- Did another compression check (Perfect)
- Ran the engine in the shop. (no water test)

Result:
Picked it up last night and ran through the same scenario. 25 minutes of speed areas and no wake zones. Speed to the area to gear up and stop and guess what, it still does it. It wasn't as bad at first but it got worse and back to what it was doing the first time. 9 to 8, 9 to 8 on the tack.

I tried to pull my son on the wakeboard with the Perfect Pass and the engine problem is even messing with that now. Everytime he pulls to make his cut it slows the boat down and the engine cant react quick enough and he hits the wake at 3 mph less than he should. I had to pull him manually.

Additional Information:
- Obviously the dealer didn't water test it long enough to get it hot enough
- Running it in the shop wont get it hot enough
- temp gauge shows a hair below 160 when warm and around 140 when cooled.
- I spoke to the dealer while on the lake and they think it might be the Coolant Temperature Sensor. The wire was lose so I fixed that but it did not correct it.
- It did seem to run better after it sat for 15 minutes while I was fixing that wire, but it didn't last. To me that says temperature....

Next Steps:
The dealer is hoping to order a new Coolant Temperature Sensor (not a standard GM part) because they think there may be a conflict between what the gauge is saying and the sensor is saying which is messing with the computer control.

The dealer is perplexed and if this sensor doesn't fix the problem then they said they might start tearing into the engine, and I don't really want that cost. :shocked:

On a side note:
- It now runs worse then it did when I first took it in
- The dealer has not charged me for the labor during the second visit
- The compression checks show an almost perfect engine.

So here I am asking for some serious assistance from all you. Hopefully someone has been through this problem. :popcorn:

Double D
07-02-2010, 10:39 AM
Here are two pictures of the engine I took last night for the dealer so they could figure out which sensor was which.

helton333
07-02-2010, 11:12 AM
I had a similar issue, we did all the same and the only thing you haven't mentioned, coil, we changed out - that fixed ours.

Double D
07-02-2010, 01:30 PM
I had a similar issue, we did all the same and the only thing you haven't mentioned, coil, we changed out - that fixed ours.

Yep, did not change coil. With the warm up period it makes me wonder how it could be a coil. I don't see that being effected by heat. :confused:

rspiecha
07-02-2010, 01:44 PM
Do you still have the water/fuel seperator installed??? Spin on filter looking object down below engine level, in front, port side on the rail the motor mounts on. I had mine removed to help a similiar issue when the boat was new. Installed a fuel filter at tank to clean out trash before coming into the fuel pump.

Later on, same problem came back. My final fix was to replace the throttle body with injectors which includes an integrated fuel pressure regulator. The new owner has had the boat for almost 4 years without issues.

Rob

captain planet
07-02-2010, 01:48 PM
Yep, did not change coil. With the warm up period it makes me wonder how it could be a coil. I don't see that being effected by heat. :confused:

Actually, that might be it. I have had temperature effect a coil on other engines before. The fact that you are shutting the engine off and then it acts up after restarting makes me think this might be the culprit.

pkreusch
07-02-2010, 01:51 PM
Unfortunately, coils will break down from heat. A coil will heat up over time and one that is ready to give out will sometimes act that way. They get old and the resistance changes which causes heat which in turn causes more resistance which in turn causes more heat which in turn......well you get the picture.

rspiecha
07-02-2010, 01:55 PM
Here is a related thread about sensors on the boat.

http://www.mastercraft.com/teamtalk/showthread.php?t=4458&highlight=1994+Prostar

Double D
07-02-2010, 01:59 PM
Do you still have the water/fuel seperator installed??? Spin on filter looking object down below engine level, in front, port side on the rail the motor mounts on. I had mine removed to help a similiar issue when the boat was new. Installed a fuel filter at tank to clean out trash before coming into the fuel pump.

Later on, same problem came back. My final fix was to replace the throttle body with injectors which includes an integrated fuel pressure regulator. The new owner has had the boat for almost 4 years without issues.

Rob

I still have the F/W separator on the boat. I will put that on the list once the sensor and coil don't fix it.

Thanks!

Double D
07-02-2010, 02:01 PM
Actually, that might be it. I have had temperature effect a coil on other engines before. The fact that you are shutting the engine off and then it acts up after restarting makes me think this might be the culprit.

Unfortunately, coils will break down from heat. A coil will heat up over time and one that is ready to give out will sometimes act that way. They get old and the resistance changes which causes heat which in turn causes more resistance which in turn causes more heat which in turn......well you get the picture.

I never figured that. I will suggest this to the dealer and see what they say.

Well, I mentioned it to the dealer and he doesn't think that is it. He figured if it was the coil the engine would lose power at any speed, and its only idling bad. I did mention that when I used the PP I lost power but when I hold the throttle in position I don't. Also, at full speed across the lake, its fine.

Thanks!

JLeuck64
07-02-2010, 02:21 PM
Check your grounds...

Engine block.
Behind the dash there is one ground that is known to cause problems if it is loose. Especially when a boat has PP installed...

Double D
07-06-2010, 08:06 AM
Bumpidty Bump Bump.... Still waiting for the sensor but now that the 4th is over, and no boat trip, still looking for more ideas....

blackcreek
07-06-2010, 10:06 AM
Get your hands on an inductive timing light, you can probably get one at auto zone rent-a- tool or an old school mechanic. Run the boat until you get the poor running condition and then with engine running hook up the timing light sensor over each spark plug wire one at a time and check for spark. The timing light strobe will flash slow enough at idle that you can just eyeball each cylinder for proper spark. A good solid and steady flash rules out most ignition related problems except cracked spark plugs. You can also rev the motor and watch the light for any skips or drop outs. When hooked to number one wire point it at the timing marks and check that timing is not jumping around. It sounds like your basic motor is healthy you just need to find the ignition or fueling issues.
I am not sure about your exact throttle body, but you can pull the spark arrestor and check the spray pattern on the injectors while running. I worked on a volvo penta motor that had two injectors in the throttle body, yours might be the same. Both spray patterns should look the same if one is clogged a bit you will be able to tell. You can also point the timing light at the fuel injectors.http://www.chevythunder.com/gm_throttle_body_injection_pg_1.htm After you shut down the motor you also want to check for drips coming out of the bottom of each injector. A leaky or clogged injector will cause idle problems. That is all I can think of, good luck.

Double D
07-06-2010, 11:48 AM
Get your hands on an inductive timing light, you can probably get one at auto zone rent-a- tool or an old school mechanic. Run the boat until you get the poor running condition and then with engine running hook up the timing light sensor over each spark plug wire one at a time and check for spark. The timing light strobe will flash slow enough at idle that you can just eyeball each cylinder for proper spark. A good solid and steady flash rules out most ignition related problems except cracked spark plugs. You can also rev the motor and watch the light for any skips or drop outs. When hooked to number one wire point it at the timing marks and check that timing is not jumping around. It sounds like your basic motor is healthy you just need to find the ignition or fueling issues.
I am not sure about your exact throttle body, but you can pull the spark arrestor and check the spray pattern on the injectors while running. I worked on a volvo penta motor that had two injectors in the throttle body, yours might be the same. Both spray patterns should look the same if one is clogged a bit you will be able to tell. You can also point the timing light at the fuel injectors.http://www.chevythunder.com/gm_throt...ction_pg_1.htm After you shut down the motor you also want to check for drips coming out of the bottom of each injector. A leaky or clogged injector will cause idle problems. That is all I can think of, good luck.


Prior to taking it to the shop the first time I used a timing light on each plug to check to make sure there was no erratic behavior. We did detect it once but moved the plug and it went away. The dealer did change out the timing control module during the first repair because they couldn't get it timed properly.

At the time I did the timing light test there was no pulsing idle problem, just a rough running engine.

The dealer said the throttle body spray pattern looks good and sees no erratic spray.

Next time out I will take the timing light and check for dripping. Thanks!

captain planet
07-07-2010, 01:45 PM
Sorry D your boat isn't back yet. You missed a busy lake. It was crazy. I hope Don can get it figured out for you.

Double D
07-07-2010, 06:36 PM
Sorry D your boat isn't back yet. You missed a busy lake. It was crazy. I hope Don can get it figured out for you.

I hope so. :( Waiting for that new sensor and I can try it again! I think I will suggest that Don or Chris take a ride with me....

Footin
07-07-2010, 07:06 PM
Make Chris go, he doesn't anything anyways! hahahaha:D:D:D:D

AZDave
07-07-2010, 07:57 PM
Ok, this is one that got me on my Prostar. Has the gas tank ever been removed and cleaned out. Mine had a small crack in the tubing that connected to the pick up screen. Intermittant lousy idle and acceleration. Other than that, has any fuel lines been routed near the engine block? And finally, cap and rotor, if not new you never know. Good luck.

Double D
07-07-2010, 08:11 PM
Make Chris go, he doesn't anything anyways! hahahaha:D:D:D:D

I like it!!

Ok, this is one that got me on my Prostar. Has the gas tank ever been removed and cleaned out. Mine had a small crack in the tubing that connected to the pick up screen. Intermittant lousy idle and acceleration. Other than that, has any fuel lines been routed near the engine block? And finally, cap and rotor, if not new you never know. Good luck.

I have never removed and cleaned the gas tank. I assume the pick-up screen is in the bottom of the tank? So this crack caused fuel pressure problems??
No fuel lines have be re-routed recently and the cap and rotor are new. Thanks for the thoughts!

captain planet
07-13-2010, 02:44 PM
So this should move you back up so you don't have to dig.

So.....Has Don or Chris figured it out yet? If you can keep Chris from chewing the fat with people he might be able to get some work done!

TX.X-30 fan
07-13-2010, 03:00 PM
So this should move you back up so you don't have to dig.

So.....Has Don or Chris figured it out yet? If you can keep Chris from chewing the fat with people he might be able to get some work done!




If it is the hubs just remove a wheel up frong and grab the lugs to check for play..........:D

Double D
07-13-2010, 03:09 PM
So this should move you back up so you don't have to dig.

So.....Has Don or Chris figured it out yet? If you can keep Chris from chewing the fat with people he might be able to get some work done!

Nothing figured out yet. I have been waiting two weeks for this sensor that does or doesn't exist on my engine. They ordered the correct part but thought it was the wrong part so they ordered the wrong part and now they have both. Confused?? No one, except RSPIECHA (thanks to his thread), could tell me where this sensor was located. As Don says, finding the correct information on a boat engine is a lot harder than finding it for a car.

However, the sensor is at the shop and I need to either take the boat up or go pick it up so I can put it in and get it tested again. I told Chris that he should be ready for a test drive on Friday so he can see if the problem persists or gets corrected. Of course he tells me that he may be out (chewing the fat) in a new X15 he just sold, so we can see where my little 94 - 205 rates. :D

All I know is Summer Baseball at Jackson is over after Thursday night and I need to get this boat running smooth.

Ethomass
07-15-2010, 09:30 AM
I've been following this thread because I too am have rough running engine issues. I have a 2001 PS 205v. Brand new engine, long block (old one hydrolocked and was not salvageable). When i got the boat back was riding aroudn for an hour just fine and then nothing. Ignition module went up. Got boat back and was now running, until you put into gear, stumbles and sometimes stalls. Now has progressed where when accelerating between rpms 1500-2500 there is a big hesitation. This problem seems similar to yours, and I hope your able to find a solution and get back on the water.

Double D
07-15-2010, 09:35 AM
I've been following this thread because I too am have rough running engine issues. I have a 2001 PS 205v. Brand new engine, long block (old one hydrolocked and was not salvageable). When i got the boat back was riding aroudn for an hour just fine and then nothing. Ignition module went up. Got boat back and was now running, until you put into gear, stumbles and sometimes stalls. Now has progressed where when accelerating between rpms 1500-2500 there is a big hesitation. This problem seems similar to yours, and I hope your able to find a solution and get back on the water.

Tomorrow should be my next test. As long as the weather cooperates I will put the sensor in and take it for another lost test drive. Fingers are crossed!

JimN
07-15-2010, 09:51 AM
Nothing figured out yet. I have been waiting two weeks for this sensor that does or doesn't exist on my engine. They ordered the correct part but thought it was the wrong part so they ordered the wrong part and now they have both. Confused?? No one, except RSPIECHA (thanks to his thread), could tell me where this sensor was located. As Don says, finding the correct information on a boat engine is a lot harder than finding it for a car.

However, the sensor is at the shop and I need to either take the boat up or go pick it up so I can put it in and get it tested again. I told Chris that he should be ready for a test drive on Friday so he can see if the problem persists or gets corrected. Of course he tells me that he may be out (chewing the fat) in a new X15 he just sold, so we can see where my little 94 - 205 rates. :D

All I know is Summer Baseball at Jackson is over after Thursday night and I need to get this boat running smooth.

Which sensor?

Double D
07-15-2010, 10:30 AM
Which sensor?

Its the temperature sensor that sends info to the ECM. Its a long story why it is taking so long but they weren't sure where it was located therefore they weren't sure if they ordered the right one.

captain planet
07-15-2010, 10:38 AM
Tomorrow should be my next test. As long as the weather cooperates I will put the sensor in and take it for another lost test drive. Fingers are crossed!

You have a rain suite correct? Bring one for Chris. Your carpet will dry out eventually. ;)

Double D
07-15-2010, 11:25 AM
You have a rain suite correct? Bring one for Chris. Your carpet will dry out eventually. ;)

Your invited to help out!

Double D
07-16-2010, 10:13 PM
Well the sensor was replaced, took 2 minutes, and took it to the lake. Told Chris from BHM that if I had problems I would call him. So I ran it through the same scenario; 3 fast areas, 2 long no wake zones right before our ski area. The thing ran great to that point. Entered our ski area and drove up to the corner to suit up (2 minutes @35 mph). With in 30 seconds of stopping the idle started pulsing up and down again. The sensor didn't work.

We did get a new symptom: when is was idling bad and it stalled when I put it in gear, it would not restart for at least 10 to 15 minutes. This happened twice today......

Called Chris at 11:00 and he finally made it at 5 PM. Hooked up the computer to the engine and took several readings. He has to investigate those readings but he did say that the MAP was only getting 2 volts and it should be at 5 volts.

Who knows!!! Very frustrated and still don't know how to fix it. I'm happy Chris was able to get down and now he is involved so maybe he will come up with something.

JimN
07-16-2010, 10:20 PM
Well the sensor was replaced, took 2 minutes, and took it to the lake. Told Chris from BHM that if I had problems I would call him. So I ran it through the same scenario; 3 fast areas, 2 long no wake zones right before our ski area. The thing ran great to that point. Entered our ski area and drove up to the corner to suit up (2 minutes @35 mph). With in 30 seconds of stopping the idle started pulsing up and down again. The sensor didn't work.

We did get a new symptom: when is was idling bad and it stalled when I put it in gear, it would not restart for at least 10 to 15 minutes. This happened twice today......

Called Chris at 11:00 and he finally made it at 5 PM. Hooked up the computer to the engine and took several readings. He has to investigate those readings but he did say that the MAP was only getting 2 volts and it should be at 5 volts.

Who knows!!! Very frustrated and still don't know how to fix it. I'm happy Chris was able to get down and now he is involved so maybe he will come up with something.

As I posted before, the grounds need to be checked. If the MAP sensor voltage reference was to a bad ground that happened to be the one the ECM uses, it should throw a code. Again, all voltage and ground references are to the battery posts, not the cable clamps.

I would also recommend that a voltage drop test be done. There are some shared grounds too, and they should be checked out.

Footin
07-16-2010, 10:21 PM
I thought 2 volts at idle was about right?

JimN
07-16-2010, 10:25 PM
I thought 2 volts at idle was about right?

That depends on where it's being measured. If it's 2VDC going to the MAP sensor, it's a problem but if it's 2VDC from it, it's not.

Double D
07-16-2010, 10:28 PM
As I posted before, the grounds need to be checked. If the MAP sensor voltage reference was to a bad ground that happened to be the one the ECM uses, it should throw a code. Again, all voltage and ground references are to the battery posts, not the cable clamps.

I would also recommend that a voltage drop test be done. There are some shared grounds too, and they should be checked out.

I thought 2 volts at idle was about right?

That depends on where it's being measured. If it's 2VDC going to the MAP sensor, it's a problem but if it's 2VDC from it, it's not.

Thanks guys! I will forward Chris this thread to give him your input.

captain planet
07-17-2010, 10:30 PM
DD, sorry to hear about your troubles. That's a bummer. If it makes you feel better, I just spent all day packing at my house, called my footin buddy for tomorrow and told him I wasn't coming in the morning because I have to pack more. I just got back from dropping off a load of crap in storage.

Is Chris losing his edge? :rolleyes:

Double D
07-17-2010, 10:57 PM
DD, sorry to hear about your troubles. That's a bummer. If it makes you feel better, I just spent all day packing at my house, called my footin buddy for tomorrow and told him I wasn't coming in the morning because I have to pack more. I just got back from dropping off a load of crap in storage.

Is Chris losing his edge? :rolleyes:

Yeah that sucks for you!! Didn't pack up the computer yet I see??

No, I cant say Chris has lost his edge, he just hasn't really been involved yet.... Now he is!

Hitting Salt Fork tomorrow with the brother and the family. Just dealing with the idle issue for now.

Double D
07-20-2010, 09:26 AM
This sucks! I thank everyone for the advice so far but it figures my problem would happen after Harold left for good, and where the heck have the comments been from the BAWS guys??

My man Chris is waiting to hear back from MasterCraft but I still have a crappy running ship.... Going on almost two months now.....:(

JimN
07-20-2010, 10:07 AM
This sucks! I thank everyone for the advice so far but it figures my problem would happen after Harold left for good, and where the heck have the comments been from the BAWS guys??

My man Chris is waiting to hear back from MasterCraft but I still have a crappy running ship.... Going on almost two months now.....:(

I just looked at your first post and I see a problem. You stated that the ECT isn't a standard GM part and that's wrong. These motors went to Indmar from the regular GM assembly line and there's no difference between that ECT and one on a regular GM car or truck. Second, the photo shows a tan/black wire going to the sensor on the top of the thermostat housing, with blue tape on it. That's WRONG!. That sensor has two wires on it and they're supposed to be yellow and black. If that sensor has two wires and they were twisted together, then connected to the tan/black wire, that's A) a bad repair and B) going to cause a problem when the ECM sees the voltage. If someone hasn't though to call MC for the correct part number, I have to wonder why.

If the shop wants to tear into the motor, it means they don't know this motor. It's not that hard to get info on it and if the diagnostic computer was actually connected, there's no way in hell it showed the correct temperature.

It's a simple system and any GM mechanic can fix it. Any MC tech should be able to fix it, too. If not, they need to go to training or take it upon themselves to find out how this stuff works. The diagnostic section in the manual is the same as what's in a Haynes or Chilton manual, except for the 02/Cat info and a few other minor things.

If it was actually connected to a diagnostic computer and it has a bad sensor, it would have shown up. If it has a bad ground on the motor, it would be seen as low voltage to the ECM and if that's compared to what is measured at the battery, it should be different.

"Increased the timing a bit"? How? Was it in Diagnostic Mode when this was done? If not, there's no way it's accurate, unless by luck. The timing mark would have been jumping all over the place if it wasn't in Diagnostic mode.

You posted that the compression was "perfect". What were the numbers?

Was the fuel pressure checked? If the people working on it went to any MC training, the first thing drilled into their heads was "80% of all driveability issues are fuel-related". This means pressure, volume and fuel quality. If the pressure hasn't been checked, do that now.

Verify the timing order. If it runs rough at idle, it could be wrong. It happens. It could also be a bad plug or plug wire. If the base of the distributor is dirty and not making good contact with the block, the IC module won't operate correctly.

coz
07-20-2010, 10:14 AM
Any MC tech should be able to fix it

Sounds like the MC techs can't so I wonder why you don't go to an Indmar tech? Why are you dealing with a dealer that's incapable of getting you back on the water?....probably an easy fix for someone that knows what the hell their doing.

JimN
07-20-2010, 10:33 AM
Sounds like the MC techs can't so I wonder why you don't go to an Indmar tech? Why are you dealing with a dealer that's incapable of getting you back on the water?....probably an easy fix for someone that knows what the hell their doing.

If they are a MC dealer, they need to get with the program.

Double D
07-20-2010, 10:47 AM
I just looked at your first post and I see a problem. You stated that the ECT isn't a standard GM part and that's wrong. These motors went to Indmar from the regular GM assembly line and there's no difference between that ECT and one on a regular GM car or truck. Second, the photo shows a tan/black wire going to the sensor on the top of the thermostat housing, with blue tape on it. That's WRONG!. That sensor has two wires on it and they're supposed to be yellow and black. If that sensor has two wires and they were twisted together, then connected to the tan/black wire, that's A) a bad repair and B) going to cause a problem when the ECM sees the voltage. If someone hasn't though to call MC for the correct part number, I have to wonder why.

If the shop wants to tear into the motor, it means they don't know this motor. It's not that hard to get info on it and if the diagnostic computer was actually connected, there's no way in hell it showed the correct temperature.

It's a simple system and any GM mechanic can fix it. Any MC tech should be able to fix it, too. If not, they need to go to training or take it upon themselves to find out how this stuff works. The diagnostic section in the manual is the same as what's in a Haynes or Chilton manual, except for the 02/Cat info and a few other minor things.

If it was actually connected to a diagnostic computer and it has a bad sensor, it would have shown up. If it has a bad ground on the motor, it would be seen as low voltage to the ECM and if that's compared to what is measured at the battery, it should be different.

"Increased the timing a bit"? How? Was it in Diagnostic Mode when this was done? If not, there's no way it's accurate, unless by luck. The timing mark would have been jumping all over the place if it wasn't in Diagnostic mode.

You posted that the compression was "perfect". What were the numbers?

Was the fuel pressure checked? If the people working on it went to any MC training, the first thing drilled into their heads was "80% of all driveability issues are fuel-related". This means pressure, volume and fuel quality. If the pressure hasn't been checked, do that now.

Verify the timing order. If it runs rough at idle, it could be wrong. It happens. It could also be a bad plug or plug wire. If the base of the distributor is dirty and not making good contact with the block, the IC module won't operate correctly.

Sounds like the MC techs can't so I wonder why you don't go to an Indmar tech? Why are you dealing with a dealer that's incapable of getting you back on the water?....probably an easy fix for someone that knows what the hell their doing.

Wow, I didn't mean to start a dealer bashing. I have confidence in my dealer to figure it out. If it was an easy fix we would all have the answer and it would be done. Even by your list of ideas there is not one thing that jumps out and says, "THAT IS THE PROBLEM".


The timing was done in diagnostic mode. Has it been checked when the problem kicks in, no.
Read further and you will see the sensor was located on the starboard side of the engine on the head. This is not a normal spot for this sensor and the sensor with the blue tape is for the light on the dash. Hence the confusion.
The cap & rotor were changed, the plugs are new, the wires have been tested, and it only happens after it gets nice and warm. First starts it runs fine until about 20 minutes...


Picture of the sensor location below: And this sensor has been replaced....

JimN
07-20-2010, 11:21 AM
Wow, I didn't mean to start a dealer bashing. I have confidence in my dealer to figure it out. If it was an easy fix we would all have the answer and it would be done. Even by your list of ideas there is not one thing that jumps out and says, "THAT IS THE PROBLEM".


The timing was done in diagnostic mode. Has it been checked when the problem kicks in, no.
Read further and you will see the sensor was located on the starboard side of the engine on the head. This is not a normal spot for this sensor and the sensor with the blue tape is for the light on the dash. Hence the confusion.
The cap & rotor were changed, the plugs are new, the wires have been tested, and it only happens after it gets nice and warm. First starts it runs fine until about 20 minutes...


Picture of the sensor location below: And this sensor has been replaced....

That should have two sensors for temperature- one for the ECM and one for the gauge. If it has a separate temperature light, that would explain the upper one but using tape for the connection is a bad way to do that and I can't think of a reason to not use the other one-wire sensor for the gauge and a separate light. If it has only one check engine light, that's supposed to be connected to the ECM's output.

The ECT IS located on the side. If the harness hasn't been modified, that's where it was from the beginning and it's the same sensor they always used. Again, if they didn't call MC for the correct part number, I have to wonder why. Maybe they haven't been a MC dealer for a long time but they need to at least get a copy of the manual.

Diagnostics takes time when the problem may have a thermal component. It can be a connection, a sensor, wires, a module or the pump. Have you re-checked the oil cooler, cooling hoses and impeller?

If it doesn't idle velvet smooth when it's cold, it has a problem, usually with spark. Whether it's a plug, wire, cap, rotor, IC module or firing order remains to be seen. If everything is right, this motor is extremely smooth at idle. Don't be afraid to suspect parts that were replaced. AC MR43T is the correct plug. Don't go cheap and don't let them force you to use something else- these are made for hard use in marine environments.

We were taught that the first four steps in diagnosing a driveability issue:

1) Verify the complaint.
2) Once the complaint has been verified, do a visual inspection. Do a 'wiggle test' of all connections and wires.
3) Run diagnostics- if anything shows up, address it. This includes ALL fuel, spark, compression, electrical and other mechanical tests.
4) Replace any bad parts and verify that the issue has been eliminated.

Mechanical problems are easy. It's the electrical/electronic ones that give most techs fits. I saw that the first time I went to MC training- guys with great reputations for carbureted motors looked at a relay like they were a dog watching TV. They learned but it was foreign territory for them.

One of the best classes offered was 'On-water, advanced diagnostics. They reinforced the basics and then created "Cranks, but no fire" problems on the various boat models, which we had to solve. We had three people in each group and it was a great way to streamline the process.

Maybe he needs to get together with someone else to get the ideas flowing.

Sorry, but I'm intolerant of dealers who don't send their techs to training. There's no gray area, IMO. If they don't, they're doing a huge disservice to their customers and I don't care what brand is being discussed- ALL dealers should have trained techs. I don't know who this dealer is or how long they have sold MC but if they want to be able to service MC, they should be able to service ALL MC, not just the new ones.

I'm not where the boat is and I can't see what was done to diagnose the issue(s) but if everything I posted is done, the problem will be found. It absolutely MUST be tested when the problem shows up, including timing. If it's not at 10BTDC base timing, have him set it to that. If it's not advancing to the correct maximum at high RPM or when using the diagnostic computer, it could easily be a bad distributor ground or the IC module. There's still a possibility that it's a bad connection between the ECM and IC module, too. Vibration and heat can cause wires to sag and break their connection.

Have him open and close the IAC. If it doesn't function normally, he needs to check it. This is part of the normal diagnostics when an idle issue is present.

If this problem coincides with any accessory installation, the best place to start is by removing the connections that could be causing this.

coz
07-20-2010, 11:43 AM
Have him open and close the IAC. If it doesn't function normally, he needs to check it. This is part of the normal diagnostics when an idle issue is present.


I can't believe this wouldn't be the first thing they check if it's an idle problem....remind your dealer IAC stand for Idle Air Conrol and this might be the problem.

JimN
07-20-2010, 11:48 AM
I can't believe this wouldn't be the first thing they check if it's an idle problem....remind your dealer IAC stand for Idle Air Conrol and this might be the problem.

Bad fuel pressure/quality, bad injector(s) and crossfire can cause the same thing. The wires on my truck were causing intermittent idle issues on my truck and I figured it out while I was in a drive-through lane, when I heard an odd snapping sound. If I gunned it, it went away for a while but came back. It idled like crap at the time and it's like new, now.

captain planet
07-21-2010, 01:37 PM
Are you boating yet DD?

Double D
07-21-2010, 02:46 PM
Are you boating yet DD?

I boated on Sunday with the family and it was a chore. When I was in No-Wake areas I had to hold the R's at 10 (still made a lot of wake), and when I was picking up a skier I kept the idle up and went in circles around them until they were ready. It idled bad most of the time and stalled twice.

Still waiting to hear from Chris on the readings he took last Friday.

captain planet
07-26-2010, 10:33 PM
I passed you on Wales in front of Shady Holloy tonight and you were towing the boat. So.......did it go well?

Double D
07-26-2010, 10:44 PM
I passed you on Wales in front of Shady Holloy tonight and you were towing the boat. So.......did it go well?

Was this at 4:30 PM or at 9 PM??

It went OK. My first purchase will be the IAC which was having some real strange readings. They are doing what they can to diagnose it without having me spend and spend on parts.

I did learn that West Branch is a cleaner lake, but it doesn't have the channel. Still prefer Berlin.

captain planet
07-26-2010, 10:53 PM
Was this at 4:30 PM or at 9 PM??

It went OK. My first purchase will be the IAC which was having some real strange readings. They are doing what they can to diagnose it without having me spend and spend on parts.

I did learn that West Branch is a cleaner lake, but it doesn't have the channel. Still prefer Berlin.

It was at 9. I was taking another load of stuff from the house.

Did you get the photos of big moe?

Footin
07-26-2010, 10:54 PM
Family boating = West Branch

Footin and skiing = Berlin


I would still replace the plug wires even though they tested good, are they original?

Double D
07-26-2010, 10:59 PM
It was at 9. I was taking another load of stuff from the house.

Did you get the photos of big moe?

You notice I had no lights on?? The running lights on the darn trailer are now on the fritz. Brakes and signals work... More to work on...

Got the photo's, found it on Google maps, and responded to your mail. Thats just crazy having large objects under water out there..

Double D
07-26-2010, 11:00 PM
Family boating = West Branch

Footin and skiing = Berlin


I would still replace the plug wires even though they tested good, are they original?

Agreed on all three comments!

Footin
07-29-2010, 08:44 PM
Any updates?

Double D
07-30-2010, 06:47 PM
Any updates?

Yep! It's not the coil and its not the IAC!! :confused:

Footin
07-30-2010, 06:51 PM
Did you try new plug wires? I only ask because they may check ok when cold, but build resistance when the get hot.

Just a guess....

Double D
08-01-2010, 03:24 PM
Did you try new plug wires? I only ask because they may check ok when cold, but build resistance when the get hot.

Just a guess....

Put on new wires yesterday and tried it on the lake this morning. Didn't work! :( Next is to remove the intake and replace the gasket. Leaning towards doing it myself to get it done quickly.

JimN
08-01-2010, 03:30 PM
Needs some help guys. I will try to make this short and precise so you don't lose track.

Equipment:
1994 ProStar 205
350 CI Indmar, 275 HP
Throttle Body Fuel Injection

History:
July 2009 filled up with gas at Marina. Started running rough at idle so I thought I got bad gas.

My Fixes:
- Put in treatment in Gas.
- Ran tank empty
- Changed Gas/Water Separator
- Changed Thermostat
- Changed Plugs
- Changed Fuel Filter
- Tested Plug Wires

Result:
Still runs very rough at low idle. Stumbles when engaging to forward.

Next Step:
Took it to the local dealer where they did the following:
- Compression Tested the engine.
- Change Rotor and Cap
- Re-gapped the Plugs
- Replaced the timing control module
- Increased idle a bit
- Water tested it and said it was ready.

Result:
It started better and for the first 25 minutes of speeding and no wake it ran fine. We stopped to gear up to ski and the idle began surging, or should I say dropping. The range of idle on the RPM dial would be from 9 to 8, 9 to 8, 9 to 8 and it wouldn't stop. If you tried to put it in gear, half the time it would stall. So now it is running worse!

Next Step:
Returned it to the dealer where they did the following:
- Replaced two carburetor gaskets that were cracked and sucking air.
- replaced a clear yellow rubber vacuum hose for the map sensor
- Changed PVC Valve
- Did another compression check (Perfect)
- Ran the engine in the shop. (no water test)

Result:
Picked it up last night and ran through the same scenario. 25 minutes of speed areas and no wake zones. Speed to the area to gear up and stop and guess what, it still does it. It wasn't as bad at first but it got worse and back to what it was doing the first time. 9 to 8, 9 to 8 on the tack.

I tried to pull my son on the wakeboard with the Perfect Pass and the engine problem is even messing with that now. Everytime he pulls to make his cut it slows the boat down and the engine cant react quick enough and he hits the wake at 3 mph less than he should. I had to pull him manually.

Additional Information:
- Obviously the dealer didn't water test it long enough to get it hot enough
- Running it in the shop wont get it hot enough
- temp gauge shows a hair below 160 when warm and around 140 when cooled.
- I spoke to the dealer while on the lake and they think it might be the Coolant Temperature Sensor. The wire was lose so I fixed that but it did not correct it.
- It did seem to run better after it sat for 15 minutes while I was fixing that wire, but it didn't last. To me that says temperature....

Next Steps:
The dealer is hoping to order a new Coolant Temperature Sensor (not a standard GM part) because they think there may be a conflict between what the gauge is saying and the sensor is saying which is messing with the computer control.

The dealer is perplexed and if this sensor doesn't fix the problem then they said they might start tearing into the engine, and I don't really want that cost. :shocked:

On a side note:
- It now runs worse then it did when I first took it in
- The dealer has not charged me for the labor during the second visit
- The compression checks show an almost perfect engine.

So here I am asking for some serious assistance from all you. Hopefully someone has been through this problem. :popcorn:

I see that you have a '94 Indmar motor, then you mention that it had two cracked carb gaskets. If you mean Throttle Body gaskets, I understand. The thing that bothers me is, you indicate that the idle was increased. THIS ISN'T ADJUSTABLE!!!!!!!!!!! This motor uses the IAC to set/maintain idle speed and that screw, which I hope wasn't altered, is only a throttle level rest.

I have some major problems with what has been done so far.

I have a worksheet for EFI diagnostics that we got at the first training session- I'll post it later.

Here's a tip for them- drizzle some gas into the throttle body when it bogs- I use an old mustard bottle with the adjustable tip. If it runs better, it's a fuel issue. If it runs worse, it may be a control issue. Either way, what they're doing to diagnose it isn't logical, systematic, or working. Just deciding to remove the intake manifold so the gasket can be replaced makes no sense. Unless it overheated incredibly badly, that gasket is fine. If it overheated badly enough to toast the intake gasket, the head gaskets are toast, too.

OBJECTIVE TESTING is needed, not guessing by the tech. Has a substitute fuel source (tank) been used? If not, why not? Your fuel pickup tube should have been checked at the very beginning of this ordeal. The fuel line attaches to this via an anti-siphon valve. That should have been checked, too. Also, the fuel line from the tank to the pump should have been checked. If it runs OK at first and not after 15 minutes or more, the gas tank vent should have been checked.

I have a TBI fuel pressure test block that can be connected in line, before the throttle body. Let me know if they need it. Otherwise, they should get a section of fuel line and put a Shrader valve on it so they can test the pressure, which I suspect is low.

A motor needs three things to run- compression, spark (preferably, at the right time in the cycle) and fuel/air mixed correctly. Period. This TBI system isn't that complex that it should cause this much grief. If they don't have a shop manual from MC, they need to get one.

Double D
08-01-2010, 04:07 PM
I see that you have a '94 Indmar motor, then you mention that it had two cracked carb gaskets. If you mean Throttle Body gaskets, I understand. The thing that bothers me is, you indicate that the idle was increased. THIS ISN'T ADJUSTABLE!!!!!!!!!!! This motor uses the IAC to set/maintain idle speed and that screw, which I hope wasn't altered, is only a throttle level rest.

I have some major problems with what has been done so far.

I have a worksheet for EFI diagnostics that we got at the first training session- I'll post it later.

Here's a tip for them- drizzle some gas into the throttle body when it bogs- I use an old mustard bottle with the adjustable tip. If it runs better, it's a fuel issue. If it runs worse, it may be a control issue. Either way, what they're doing to diagnose it isn't logical, systematic, or working. Just deciding to remove the intake manifold so the gasket can be replaced makes no sense. Unless it overheated incredibly badly, that gasket is fine. If it overheated badly enough to toast the intake gasket, the head gaskets are toast, too.

OBJECTIVE TESTING is needed, not guessing by the tech. Has a substitute fuel source (tank) been used? If not, why not? Your fuel pickup tube should have been checked at the very beginning of this ordeal. The fuel line attaches to this via an anti-siphon valve. That should have been checked, too. Also, the fuel line from the tank to the pump should have been checked. If it runs OK at first and not after 15 minutes or more, the gas tank vent should have been checked.

I have a TBI fuel pressure test block that can be connected in line, before the throttle body. Let me know if they need it. Otherwise, they should get a section of fuel line and put a Shrader valve on it so they can test the pressure, which I suspect is low.

A motor needs three things to run- compression, spark (preferably, at the right time in the cycle) and fuel/air mixed correctly. Period. This TBI system isn't that complex that it should cause this much grief. If they don't have a shop manual from MC, they need to get one.

JimN,

Idle increase. I only stated what the first guy told me. In later tests when the idle is fine, its hanging around 600.

To my knowledge, none of the fuel stuff you mention has been done. I don't understand how a fuel issue pops up with heat. Can you help me understand that?

So your opinion is to NOT tear into the intake yet?? What is my next test while its sitting in my garage?

Thanks!

JimN
08-01-2010, 04:32 PM
JimN,

Idle increase. I only stated what the first guy told me. In later tests when the idle is fine, its hanging around 600.

To my knowledge, none of the fuel stuff you mention has been done. I don't understand how a fuel issue pops up with heat. Can you help me understand that?

So your opinion is to NOT tear into the intake yet?? What is my next test while its sitting in my garage?

Thanks!

Look at the fuel system, from back to front. check the fuel pressure. Make sure the plugs are the right ones (I don't remember seeing the brand or number, but they should be AC MR43TS). Make sure the flame arrestor is clean. If you feel like it, spray the outside of the injectors with carb cleaner. I do this and it smooths the idle on my truck. Verify the firing order again. Make sure the plug wires are pushed all the way onto the distributor cap and the plugs. Run it at night and watch for sparks- if you see any, the wires are bad, even though you posted that they were replaced.

Double D
08-01-2010, 05:14 PM
Look at the fuel system, from back to front. check the fuel pressure. Make sure the plugs are the right ones (I don't remember seeing the brand or number, but they should be AC MR43TS). Make sure the flame arrestor is clean. If you feel like it, spray the outside of the injectors with carb cleaner. I do this and it smooths the idle on my truck. Verify the firing order again. Make sure the plug wires are pushed all the way onto the distributor cap and the plugs. Run it at night and watch for sparks- if you see any, the wires are bad, even though you posted that they were replaced.

Still need to understand how heat effects fuel problem.
Front to back. Check what in the tank? How do I know there is a problem? I replaced the fuel filter. How do I test fuel pressure?

Plug wires on pushed on tight since I just replaced them.

Trying to accomplish things on my own so I don't lose any more time. Thanks!

Double D
08-01-2010, 08:55 PM
OK, I talked with my neighbor who is a great car mechanic and his step father owns a boat shop. He is going to get me a fuel pressure gauge to test the fuel pressure. He does not think the cast iron intake would be cracked but cant rule out the gasket, or the centering O-Ring. When I was talking to him I did remind myself that I did run so low on gas that it wouldn't start so I could have effected the fuel pump. The heat aspect still confuses me.

JimN, can you tell me what he fuel pressure should be? Confirm for me that the fuel pump is in the tank and how how hard it is to replace?

Thanks! BTW, the engine never overheated.

JimN
08-01-2010, 10:50 PM
Still need to understand how heat effects fuel problem.
Front to back. Check what in the tank? How do I know there is a problem? I replaced the fuel filter. How do I test fuel pressure?

Plug wires on pushed on tight since I just replaced them.

Trying to accomplish things on my own so I don't lose any more time. Thanks!

I posted before about putting a Shrader valve on the fuel line if it doesn't have one. It looks just like a tire valve but it needs to be safe with liquids like gasoline. A good parts store can set you up- this needs to use compression fittings because of the pressure involved. Once the pressure has been tested, it comes off and the fuel lines go back where they were before. This should be a T fitting because the pressure should be tested at Key ON/Engine OFF, idle, 2000 RPM and WOT. A fuel pressure gauge can be bought for less than $40 or borrowed from a parts store like Auto Zone.

The anti-siphon valve is a check valve- a metal piece that threads into the fuel pickup with a ball and spring. If there's any corrosion,if the ball can't move freely, if there's any debris, it needs to be repaired or replaced. It should not be removed- this is for cases when the fuel line is damaged and leaks, to keep the fuel from draining out of the tank by siphoning. I listed the other things that should be tested.

Your pump is on the side of the motor. It also has a screen on the inlet side and this should be cleaned. There are many threads here about how to do this.

Double D
08-06-2010, 11:07 PM
Update:
I had no location to test the fuel pressure so I purchased a new fuel pump since I didn't think it was the intake.
Took the boat out tonight to test with the new fuel pump attached. After the usual warm up period it did it again. The idle would pulse up and down. I brought some WD40 to spray and pulled the flame arrestor from the throttle body injection and as I watched the fuel inject into the carb, the one of the right would not spray during the low idle, causing the idle problem. To test the injector I switched the plug to the other injector and the opposite injector started acting up. By spraying in the WD, it helped smooth the idle. There is a common red wire and a blue and green wire. So I was told that maybe the green wire is causing the injector to not spray right. Its either the wire, or the computer.

JimN, do you agree that I should trace the wire and test it and if that does not show or correct the problem, its the computer??

JimN
08-07-2010, 08:29 AM
Update:
I had no location to test the fuel pressure so I purchased a new fuel pump since I didn't think it was the intake.
Took the boat out tonight to test with the new fuel pump attached. After the usual warm up period it did it again. The idle would pulse up and down. I brought some WD40 to spray and pulled the flame arrestor from the throttle body injection and as I watched the fuel inject into the carb, the one of the right would not spray during the low idle, causing the idle problem. To test the injector I switched the plug to the other injector and the opposite injector started acting up. By spraying in the WD, it helped smooth the idle. There is a common red wire and a blue and green wire. So I was told that maybe the green wire is causing the injector to not spray right. Its either the wire, or the computer.

JimN, do you agree that I should trace the wire and test it and if that does not show or correct the problem, its the computer??

There's a device called a 'noid' light, for testing the injector pulses. If you have an Autozone near you, they may have this available for loan. This is needed because a multi-meter won't react fast enough to get a good indication of whether the injector drive signal is getting to the plug.

I thought I mentioned looking at the injector spray at the beginning. Hmmm. That's part of the visual inspection I always mention. Another thing to do is look at the terminals in the large plugs going to the ECM- if you see corrosion, the terminal needs to be replaced. By the time the moisture has corroded the terminal, it has done enough damage that cleaning won't work. There's only one specific terminal for this and it can't be soldered directly to the ECM pin.

Look at the metal terminal in the plastic clip on that injector- is it bent, missing or is one side bent so it can't make contact? If it is, it may need to be replaced- NAPA has the replacement terminals. It needs to be crimped with the correct crimper and soldered, in order to be a reliable repair.

If you want to test the wires from the injector, disconnect the battery cables before anything else. Then, remove the large plug marked J2. This one has less wires than J1. Test for continuity on the light green wire at pin J2-5, Dark blue J2-21, Black/White injector ground J2-15 and J2-20.

Double D
08-07-2010, 05:15 PM
There's a device called a 'noid' light, for testing the injector pulses. If you have an Autozone near you, they may have this available for loan. This is needed because a multi-meter won't react fast enough to get a good indication of whether the injector drive signal is getting to the plug.

So if there is a signal problem what does that point too?? ECM (Computer)?

I thought I mentioned looking at the injector spray at the beginning. Hmmm. That's part of the visual inspection I always mention. Another thing to do is look at the terminals in the large plugs going to the ECM- if you see corrosion, the terminal needs to be replaced. By the time the moisture has corroded the terminal, it has done enough damage that cleaning won't work. There's only one specific terminal for this and it can't be soldered directly to the ECM pin.

You did. But understand I was not doing the work. The shop also did a visual inspection but never got it HOT enough to react. There is no corrosion on any plug between the ECM and the injector.

Look at the metal terminal in the plastic clip on that injector- is it bent, missing or is one side bent so it can't make contact? If it is, it may need to be replaced- NAPA has the replacement terminals. It needs to be crimped with the correct crimper and soldered, in order to be a reliable repair.

I checked this and confirmed there is contact here.

If you want to test the wires from the injector, disconnect the battery cables before anything else. Then, remove the large plug marked J2. This one has less wires than J1. Test for continuity on the light green wire at pin J2-5, Dark blue J2-21, Black/White injector ground J2-15 and J2-20.

When we did our test today with the green wire I did not see this message yet. We ran a jumper wire from the computer plug to the injector plug and ran the boat in the driveway with the jumper unhooked. It never got HOT enough to pulse but as I was working the throttle I moved it slowly up through 1500 to 2500 RPM's and it stumbled a lot around 1800 to 2000 like a bad plug. I watched the injector and it was not spraying a nice consistent spray. So we tried the jumper wire and it did not change anything which tells me the wire is OK.

Am I looking at an new ECM? Or should I be doing your steps 1 (noid light) and 4 (J2 tests) before you can answer?

If I am do I have any reprogramming options like Mercury provides??

JimN
08-07-2010, 06:56 PM
So if there is a signal problem what does that point too?? ECM (Computer)?

You did. But understand I was not doing the work. The shop also did a visual inspection but never got it HOT enough to react. There is no corrosion on any plug between the ECM and the injector.

I checked this and confirmed there is contact here.

When we did our test today with the green wire I did not see this message yet. We ran a jumper wire from the computer plug to the injector plug and ran the boat in the driveway with the jumper unhooked. It never got HOT enough to pulse but as I was working the throttle I moved it slowly up through 1500 to 2500 RPM's and it stumbled a lot around 1800 to 2000 like a bad plug. I watched the injector and it was not spraying a nice consistent spray. So we tried the jumper wire and it did not change anything which tells me the wire is OK.

Am I looking at an new ECM? Or should I be doing your steps 1 (noid light) and 4 (J2 tests) before you can answer?

If I am do I have any reprogramming options like Mercury provides??

The noid light confirms that the pulses are getting to the injector AND good ground. You have Red/Green and Red/Blue at the injectors, right?

With the injector plugs off of the injectors, test for continuity to the block on the green wires and if you only get it with one of them, do the wiggle test, working your way back in the harness. If it fires up again, unwrap the wires and look for cuts, melted insulation or breaks at junctions. There aren't many shared wires, so this should end up being a short list.

Make note of the wires that are grounded- when it stops firing that one, insert a wire into that side of the plug, making good contact with the terminal and ground the other end. If it starts working, it's the harness and if not, I would get a noid light. If you have an LED test light (they're really cheap at Harbor Freight and places like that), insert the tip into the injector plug- you'll be using it as a noid light.

It's not toggling between the injectors, is it? That means it's in RPM reduction and is trying to save the motor.

I don't think the ECM is bad, but it's possible. No, it's not programmed the same as a Mercury and if it was fine until recently, there's no problem with the programming.

Double D
08-08-2010, 08:14 PM
The noid light confirms that the pulses are getting to the injector AND good ground. You have Red/Green and Red/Blue at the injectors, right?

With the injector plugs off of the injectors, test for continuity to the block on the green wires and if you only get it with one of them, do the wiggle test, working your way back in the harness. If it fires up again, unwrap the wires and look for cuts, melted insulation or breaks at junctions. There aren't many shared wires, so this should end up being a short list.

Make note of the wires that are grounded- when it stops firing that one, insert a wire into that side of the plug, making good contact with the terminal and ground the other end. If it starts working, it's the harness and if not, I would get a noid light. If you have an LED test light (they're really cheap at Harbor Freight and places like that), insert the tip into the injector plug- you'll be using it as a noid light.

It's not toggling between the injectors, is it? That means it's in RPM reduction and is trying to save the motor.

I don't think the ECM is bad, but it's possible. No, it's not programmed the same as a Mercury and if it was fine until recently, there's no problem with the programming.


Jim, The MAP Sensor was never replaced. Could that cause this problem? Can I purchase a MAP sensor at a local AutoZone and it will work, or does it have to be marine?

JimN
08-08-2010, 10:08 PM
Jim, The MAP Sensor was never replaced. Could that cause this problem? Can I purchase a MAP sensor at a local AutoZone and it will work, or does it have to be marine?

The MAP sensor tells the ECM the barometric pressure (that's how it can run at high and low altitude without mods, unlike a carbureted motor) and vacuum. It won't keep it from idling and it definitely won't shut an injector off. If it goes bad, it will store a code.

One thing I'll tell you- not to be mean but to get the boat running again- go to a dealer or service shop who knows the EFI system. Not knowing how it works means the troubleshooting procedures that are already established won't be followed and not only will it waste your time and money, but it will make you hate your boat. If you don't have a trusted MC dealer, find a Supra, Moomba or Malibu dealer- they all use Indmar EFI systems.

Step away from the parts cannon. It doesn't work as an efficient method of repair.

93Prostar190
08-12-2010, 10:00 AM
DoubleD ... lot a great advice in this thread to date. Some great EFI expertise by people. From a troubleshooting perspective you need to be 100% sure that the following is true:

1 - All grounds are solid ..... current (AMPS and Volts) are how they should be be. A bad ground can change the signal to or from the ECM and that will result in a problem. An electrical problem can be related to temperature.

2. You need to have the ECM checked. You need to know it is good. This may be the last step. See # 3. you also need to know that you have great fule pressure at idle, and through the RPM range. Which I would suspect you do.

3. You need to make sure the EFI is working properly. Any GM technician should be able to help you. If there is a good repair shop in your area, take them the boat and help them connect to a hoe to run it out of the water. Offering a 12-pack to the diagnostic engineer has worked for me in the past .... run it out of the water and get a EFI diag and check.

I have a feeling that you have a bad wire to an injector control module (or injector) .... so the ECM is trying to give you good idle but the injectors cannot.

Keep us posted. Good luck man!

JimN
08-12-2010, 10:14 AM
Here's a MEFI worksheet, in case anyone wants it. This isn't particularly useful if a diagnostic computer isn't connected.

Double D
08-12-2010, 11:01 AM
Here's a MEFI worksheet, in case anyone wants it. This isn't particularly useful if a diagnostic computer isn't connected.

Thanks Jim. I forwarded it along since the boat is at the shop.

Double D
08-12-2010, 09:49 PM
Well the boat is running good again. The dealer ran all the tests on the jumpers, did an extreme wiggle test, cleaned and re-did all the grounds, and checked everything and tested it. There was still problems which now points to the ECM, or an injector driver in the ECM. The ECM is designed to drive more than two injectors (maybe four) and its only driving two. So based on them talking to Indmar and them recommending to run both injectors off of one driver, the boat is running back to normal.

Do I have a ECM with a problem, yes. Do I need to spend the money on a new ECM at this moment? No. Will I run it this way for a while, probably.

Thank you all for your ideas and suggestions and especially JimN for his constant advice and long typed ideas.

I'm glad its over and I can get on with my summer, which by the way, is almost over.....:mad:

captain planet
08-16-2010, 12:32 PM
Well the boat is running good again. The dealer ran all the tests on the jumpers, did an extreme wiggle test, cleaned and re-did all the grounds, and checked everything and tested it. There was still problems which now points to the ECM, or an injector driver in the ECM. The ECM is designed to drive more than two injectors (maybe four) and its only driving two. So based on them talking to Indmar and them recommending to run both injectors off of one driver, the boat is running back to normal.

Do I have a ECM with a problem, yes. Do I need to spend the money on a new ECM at this moment? No. Will I run it this way for a while, probably.

Thank you all for your ideas and suggestions and especially JimN for his constant advice and long typed ideas.

I'm glad its over and I can get on with my summer, which by the way, is almost over.....:mad:

Look on the bright side, Berlin is still only 2.7 feet below summer pool! Glad to hear Chris got you squared away, enjoy.

Double D
08-16-2010, 06:47 PM
Look on the bright side, Berlin is still only 2.7 feet below summer pool! Glad to hear Chris got you squared away, enjoy.

Yepper, we were there Sunday morning. Once the sun came out it was HOT!

Chris was a big part but he is in sales now. :D Don got the final wire checks complete and done quickly.

MCWSkr
06-28-2011, 12:57 AM
Did you ever figure out what the issue was, I am having the same problem with my 87 Prostar 190 351?

Double D
06-28-2011, 07:50 AM
Did you ever figure out what the issue was, I am having the same problem with my 87 Prostar 190 351?

Yeah, look at Post #71. It was the ECM (computer) and one of the injector drivers went bad. So the options were a new ECM for $750 (cant just buy a new one) or run both injectors off one driver. If you only have a two barrel carb you should be fine.

Good Luck!