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View Full Version : Hot starting problems with a 94PS205


Jesus_Freak
07-04-2007, 03:35 AM
I continue to have trouble starting the PS between course sets. I am confused on the cause. Each time this has come up before on TT, it seems like vapor lock (or some related term) is used to describe the problem. I can easily see the logic in this. I propose, however, that it might be the exact opposite....too much fuel. The evidence is that when I finally do get it started (by GENTLY revving in neutral), I see smoke in the exhaust. The smoke smells strongly of fuel vapor with no hint of crankcase oil. It seems the TB injectors are slowly releasing pressure and dumping fuel while the engine is sitting still and hot, making it too rich to start. Maybe, the injectors and feed lines dont hold enough fuel such that even if they fully dumped the mixture would be too rich. I am just grasping here. It does not seem to matter whether I keep the blower running or not.

It is not the end of the world, but it is annoying and adds wear to my patience and the starter motor. Thank you in advance for advice, comments, corrections, solutions, threadjacks, etc.

rspiecha
07-04-2007, 04:10 AM
I had an original problem of hot starting on my 1994 Prostar205 275 EFI TBI, the dealer removed the water/fuel separator and installed a fuel filter at the gas tank and things were tons better till about a couple of years ago, when I had a rich smelling idle. It took replacing the throttle body with new injectors and fuel pressure regulator, $1600, to fix the issue.

Rob

André
07-04-2007, 08:35 AM
Could it be the IAC that is not opening when the engine is hot?
If it start when you crack the throttle open with the engine hot then it's dumping too much fuel.The IAC position is control by engine temp .
I had a faulty engine temp sensor on my 94 TBI.It was telling the ECM that the engine was hot when cold starting causing the injectors to dump less fuel and the air/gas ratio wasn't good to start the engine.
Maybe you could have the reverse problem with the engine temp sensor telling the ECM that the engine is cold and dumping too much fuel for a hot start...
Of couse,like usual,i'm probably wrong...

JimN
07-04-2007, 10:18 AM
If it's hard to start after a hard run, open the motor box and remove the flame arrestor and watch for gas dripping from the injectors. If they leak, it could be from deposits, so try some 3M injector cleaner if you have a Shrader valve on the fuel line. If you don't have one, add a can of Sea Foam to the gas and run it. If it only does this when it's particularly hot, open the motor box or run the blower to cool the motor down- gas expands easily and if the injectors are only slightly leaky, the expansion will cause it to start rich.

chico
07-04-2007, 05:15 PM
My 94 205 did the same thing.sometimes it would start sometimes not.the battery was 6 yrs. old so I put in a new one and starts everytime.

Jesus_Freak
07-05-2007, 12:31 PM
Thanks peeps. Great ideas.

I think I remember your comments before, Rob, but mine already has a typical fuel filter at the tank.

Jim, I probably should know what a Shrader valve is and could probably find out with some inet searching, but break it down for me please. Excellent point about vapor expanding, so it wouldnt take much vapor to dump much fuel. Either way, I will look in the TB next time.

Andre, my temp dial reads fine. Is the signal sent to the dial the same as that sent to the ECU?

André
07-05-2007, 12:38 PM
Thanks peeps. Great ideas.

I think I remember your comments before, Rob, but mine already has a typical fuel filter at the tank.

Jim, I probably should know what a Shrader valve is and could probably find out with some inet searching, but break it down for me please. Excellent point about vapor expanding, so it wouldnt take much vapor to dump much fuel. Either way, I will look in the TB next time.

Andre, my temp dial reads fine. Is the signal sent to the dial the same as that sent to the ECU?
No,they're 2 different sensors.The one for the ECM is a 2 wires sensor...I think!
Shrader valve look loke a tire valve with a cap on it.I doubt you have one,there none on my boat...

Jesus_Freak
07-05-2007, 12:48 PM
Shrader valve look loke a tire valve with a cap on it..

Oh yeah.....duuuuuuuuuuu! Thanks for taking care of me. :o

JimN
07-05-2007, 02:00 PM
I was referring to liquid fuel expanding, not vapor. If it's just vapor, it can be compressed more but a liquid can't at these line pressures(Yes, I know it can technically be compressed by about .000000006%). A leaky injector will be obvious.

Jesus_Freak
07-05-2007, 04:11 PM
...Yes, I know it can technically be compressed by about .000000006%...

I think it is 0.000000005% 8p JK.

Thanks for the advice.

JimN
07-05-2007, 04:14 PM
You counted the zeros, didn't you?

Mine was rounded up.

mess33
07-09-2007, 04:18 PM
I had a similar problem this weekend on my 97 PS205 LT1. It appeared to me to be getting too much fuel and not enough air. I removed the flame arrestor because it appeared dirty and it ran great. I put the flame arrestor back on and loosened the clamp so air could flow around the edges. No problems. I bought a K & N cleaning/recharge kit and hopefully that will solve the problem long term.

Mess

Jesus_Freak
07-29-2007, 06:55 AM
I insulated my fuel line yesterday with some of that $1.70 (for 6') foam from lowes made for covering hot water lines. I saw two fuel lines connected to the TB. The larger one comes from the fuel filter exit, and the smaller one disappears down behind the engine. I assume the larger is the feed, and the smaller is the overflow/return. Is this correct?

JimN
07-31-2007, 08:31 AM
"I assume the larger is the feed, and the smaller is the overflow/return. Is this correct?"

Yes, this is correct.

Jesus_Freak
08-04-2007, 06:00 PM
Thank you Andre and JimN for the PMs. Here is an update:

Summary: When the engine is hot and I turn the key, it immediately fires a few times. It is just enough to free the starter motor. It runs for about a nanosecond. I have to open the throttle plates while starting to keep it running. Then I see and smell fuel-rich smoke. Otherwise the engine runs and idles completely fine!

Fuel line: Insulated and no improvement.

Blower: If I run it ALL the time, it seems to help.

IAC: The pintle seems to be extending and retracting like normal; dont know how much exactly.

Injectors: No dripping after shutting off hot engine.

Temp sensor: I see two, one larger than the other. When I unplug the smaller one (likely to the ECU), there is no change in operation. What else can I do?

Butterfly plates seem to be wet after shut-off. Is this normal, too coarse a spray, too much fuel? I am betting normal with the injectors slamming them with fuel.

DLC with A and B terminals: See lots of A and B terminals on wires back there behind the engine. Which one is the DLC? How do I see the codes?

JimN
08-04-2007, 07:06 PM
If you removed the plug from the one with two wires and it didn't change the way it starts, you may have found the problem. That one reports the coolant temperature to the ECM and if it thinks the coolant is cold, it'll deliver too much fuel, making it do what you're saying it is. If you have access to a digital multi-meter, run it like normal and if the problem shows up, remove the plug and measure the resistance between the two pins in the sensor. At 176ºF, the resistance should be in the 320-350 ohm range. If it's in the 1000's of ohms or higher, the sensor needs to be replaced. You can check the resistance in a good sensor by putting it in a pan of cold water, measuring and then heating the water and re-measuring to see if there's any change. At 212ºF, it should be about 177 Ohms and at +5ºF, it should be about 7280 Ohms.

If the sensor's resistance is normal, the wires to the ECM need to be checked for breaks or corrosion on the terminals. There are two large plugs attached to the ECM and they're marked J1 and J2. The Coolant Temperature sensor is connected to J1-2 and you should be able to read close to 0 ohms from the sensor's plug (yellow wire) directly to J1-2. If it's appreciably higher, you need to look into why it's higher. If you check the sensor's ground directly to the ECM harness, measure from the sensor plug's black wire to J1-29. You can also check this by measuring from the ECT (Engine Coolant Temperature) plug to the pin that corresponds to the MAP sensor's black wire. Again, you should have very little resistance from the pin to J1-29 or to the pin corresponding to the black wire in the MAP sensor's plug.

The DLC is a black plug with a cover on it, at the rear of the motor, usually near the circuit breaker and starter. The cover will have a wire that keeps the cover attached to the plug.

If your check engine light doesn't work at all (it should), you can connect a test light across pins E and F. Insert a paperclip into A and B, then watch for the test light to blink once, twice (this is what they use to show 12), slight pause and repeat the 12. If it indicates 15 (likely) and your test of the wiring shows no problems, you have a bad sensor.

The throttle plates should have gas on them since that's the first thing it hits when the injectors open.

The DLC has ten slots for terminals. It's the only one with this many. The rest of the connectors start with A and go up, alphabetically. A has a black/white wire and B has a white/black wire. E has a brown/white wire and F is orange.

Jesus_Freak
08-11-2007, 07:21 PM
JimN, thank you for your continued advice. I checked the sensor today while connected to the engine at around 85°F and about 150°F. It was within the range you specified, extrapolated away from the numbers you posted. So...it is not that. Next, I checked the resistance from J1-2 to the yellow wire. It read anywhere from near 0 to infinity depending on how I had the J1 plug cocked. I checked it over and over, being careful to make sure my probe was touching the J1-2 terminal. I am convinced there is a problem with the contacts within the J1 plug connector itself. The J1 harness has NO slack in it, and gives absolutely no room to look at the plug. Is there a way to loosen up a clamp somewhere and work on this thing? Do I need to let a pro do this, or can you recommend something? The boat does not idle any differently with the sensor connected than when it is disconnected, so I think we are on the right track.

David Forst
08-11-2007, 07:34 PM
I have a hot starting problem also. I find only two temp sensors. One for the Temp guage and one for the idoit light. Both are only one wire units. When hot the fuel injectors donot spay any fuel unless I put starter fluild in the TBI. Then the injectors come on when the motor fires.

JimN
08-11-2007, 08:26 PM
David- Trust me, the temperature sensor that reports to the ECM has two wires. I also would recommend not using starting fluid.

What you're doing isn't particularly good for the motor and ether is too flammable/explosive to have in a boat. Your motor has a problem that can and should be repaired.

JimN
08-11-2007, 08:28 PM
If the ECM is positioned in a way that it pulls on the harness, I would look into enlarging the mounting holes and shifting it a bit. Loosen the bracket enough to remove the tension and see if the problem goes away. If it does, move the ECM over so it's not yanking on the wires.

David Forst
08-12-2007, 12:20 PM
Can you give me the location of the temp sensor for the ECM. I can find the one for the temp guage and the idoit light, both with only one wire.

Thanks for your quick answer.

I will use the other info in your post to try and find the problem. If the battery is weak and the motor turns over below 300rpm is it ture the fuel pump relay will not turn on.

Thanks again

Dave

JimN
08-12-2007, 01:02 PM
Look on the heads for a black wire loom. Opening the loom, you should see two wires- one yellow and one black. My manual shows a picture of the sensor in the intake manifold, but it's just for representation and not necessarily for marine applications. It has a black plastic receptical for the plug and will definitely have two wires.

David Forst
08-12-2007, 06:57 PM
I found the sensor. It is on the right side at the back. When hot if I unplug this sensor it start the injectors right away. Motor starts right up. If I plug it back in again when hot the injectors donot start.The engine RPM is also changed if you plug it in when running. All ground and all conections have been cleaned and check. I heard that there is a flash for the ECM for this problem.

Thanks again

Dave

JimN
08-12-2007, 08:31 PM
Have you checked the sensor's resistance yet? If the resistance is too low, it thinks the motor is overheating at that time and and if it's reading full hot, it won't start at all. Get a new sensor, or start by checking the resistance. If it's less than 300 Ohms at a normal operating temperature (like 160º- 185º), get a new one. If the ECM thinks the temperature is too high, RPM reduction kicks in, which limits it to 2000 RPM and it will be hard to start. There is no re-flash, you have a bad sensor. Your ECM is working fine.

Jesus_Freak
08-13-2007, 01:10 PM
JimN, I am bumping this to seek your response to Post #17.

EDIT: Found your response. Thanks.

JimN
08-13-2007, 02:30 PM
See post #20.

Jesus_Freak
08-30-2007, 04:52 AM
Thanks for everyone's advice. I had a dealer run the diagnostics through the DLC. Nothing was wrong. They claim the cause is the steadily increasing alcohol content in the fuel in recent years. I am supposed to get an ECM update today.

I also found out why the boat idled the same with our without the temp sensor....it is because the spark advance will jump around as necessary to make the boat idle at the ~600 idle setpoint.

JimN
08-30-2007, 08:41 AM
I would bet that the update includes opening the IAC a bit more for hot starts. They had a similar issue on the early 2001 LTR, since Rochester decided to omit the hole in the throttle plate after the development had been completed, and didn't really make it known.

Jesus_Freak
08-31-2007, 05:10 AM
I reviewed the computer diagnostics report. I think the current IAC is something like 15 or 16. I dont remember the units, maybe °? I will check it after the update and see what has changed.

I was surprised at how "dumb" the computer is. I am thankful for the EFI, but it has no air temperature detection. Without this, the density computation is going to be seriously bogus. The air density (and therefore cylinder fuel requirement) changes nearly 40% from freezing to 100°F. And, it has no loop closing ability to go and correct this once it delivers the fuel. Oh well, I guess it works...

JimN
08-31-2007, 08:53 AM
The IAC is called a 'stepper motor' and the number is just how many steps from a particular position the pintle is, and in this case, the starting position is closed.

The computer isn't dumb. With open loop calibration, there's no need, or way, to control the fuel delivery as much as they do in a car. Remember, there's no O2 sensor, no catalytic convertor, no OBDII, etc. The fuel table is based on coolant temperature, throttle angle delta, MAP and RPM. You're comparing it to a newer motor's controller and system and there's no need to do that. It was more advanced than just about any other marine system, other than custom, at the time.

If you want an IAT installed, there's a place to plug that wire into the ECM harness, but Indmar and MC may not have felt there was a need for it as long as they made it run well without. I'm not sure there's a program that includes the IAT for your year, but I can check into it. It wouldn't come from MC or Indmar, though.

Jesus_Freak
09-01-2007, 06:20 PM
Thanks JimN for the IAC info. I meant "dumb" relative to an automotive delivery calculation. My point is that an air temperature value has to be either detected or assumed to calculate air density. I would prefer it be measured instead of assumed (which could be as much as 40% different than reality). But....if it is not standard or part of a normal issue, I am not interested in trying to adapt it. Thanks for the offer. It works, and that is what I need when I am skiing.:D

By the way, the computer has been updated, and all is fixed. The cold start (which was not really broken, but not perfect) and hot start both are excellent! Thanks Indmar!:woohoo:

David Forst
09-04-2007, 02:16 AM
Like to thank you for all the advice. The temp. guage was not working and the temp was over 190 causing the block temp to go over cut off when the motor was turned off. Fix the temp guage and installed a new ther. stat and all is fine now with hot starts.

Thanks again, your advice was right on.

Dave

Perino
10-25-2010, 05:59 AM
Hi Guy, I need to pick your brains for some advise. I have a 2006 MasterCraft X1, 350MCX with 170hrs. The boat's fuel pump packed up and I replaced it with a aftermarket pump. The boat start fine when cold and runs perfectly, BUT when i try strat it when it is hot it just turns. The local guys here say it's the fuel pump, but i think it might be the temp sensors? Any advise, also where are the temp sensors located on the motor?

Thanks,

Perino

JimN
10-26-2010, 09:56 PM
Hi Guy, I need to pick your brains for some advise. I have a 2006 MasterCraft X1, 350MCX with 170hrs. The boat's fuel pump packed up and I replaced it with a aftermarket pump. The boat start fine when cold and runs perfectly, BUT when i try strat it when it is hot it just turns. The local guys here say it's the fuel pump, but i think it might be the temp sensors? Any advise, also where are the temp sensors located on the motor?

Thanks,

Perino

Open the throttle a bit and see if it starts. If it does, it could be a bad temperature sensor. It would be the one with one yellow wire and one black wire.

Davo
10-27-2010, 03:33 PM
JimN - would the boat run fine otherwise? (with a bad temp sensor)

JimN
10-27-2010, 08:27 PM
JimN - would the boat run fine otherwise? (with a bad temp sensor)

If it's running rich, it won't run as well as it should. It also wastes a lot of gas.