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Mark rsa2au
03-17-2013, 08:05 AM
Hi Guys, First post but been checking out this forum for a few months researching my next boat which I now have. A 2001 Mastercraft X5 with the 310hp TBI Indmar Preditor engine and 270 hours. It has stood for 2 years with very little run time. I live in Melbourne Australia and the local MC dealer is EXTREEMLY UNHELPFULL because I did not by my boat from them, so I do not have access to MC specific diagnostic equipment.

The engine is not very happy and last weekend used a full tank (30 Gallons) in about 2 1/2 hours. It also cuts out, runs rough and surges on half throttle. When you floor it, it pings a little on occasion but not always. After the work below it now seems to run better but with timing advanced it pings heavily on pull off and starts to back fire at about 4400rpm, then retarding the timing - no ping but backfiring at 4100. Then sometimes we will have no ping on pull off and no backfiring at 4500rpm. Max WOT seems to be 4500rpm on the origional prop. It also runs on a little after a full throttle run and shutting off after a short idle.

Initialy it was running so rich it looks like a diesel engine with the black smoke. The injectors were also sticking in full open position even with the wires removed so obviously new injectors were installed. Fuel pressure measures about 25 to 30. Plugs are new, fuel is fresh.

Next we tested and then replaced the MAF sensor with a little improvement. Temp sensor is also giving the right readings, as is the throttle position sensor. Today we noticed the idle adjusting motor was not opening / closing as it has a lumpy idle but it idles nevertheless.
Disconecting the temp sensor kills the motor, but removing the maf sensor, and the TPS does nothing and the boat runs ok with out them.

Finally after 3 weeks and 15 hour runtime (7 tanks of fuel) we have less smoke, the plugs are a tan color, and the idle is still lumpy untill we replace the above mensioned sensor / motor but it still is not what I expect.

Can any one shed any light please on what to do next to reduce the ping but stop the backfiring at high throttle openings.

1redTA
03-17-2013, 10:57 AM
have you checked the ignition control module?

Mark rsa2au
03-17-2013, 02:42 PM
have you checked the ignition control module?

No, how do I do that?

1redTA
03-18-2013, 10:22 PM
the local auto zone should be able to test it

Mark rsa2au
03-19-2013, 03:10 AM
Thanks 1redTA. The Auto Zone here in Australia does not offer that service. Might order a new unit and keep the old unit as spare. Might also look at replacing the Distributer, the plug leads and the plugs at the same time. That will eliminate a spark issue at least.

1redTA
03-19-2013, 01:12 PM
always start with the cheapest part first when replacing things on a whim

Mark rsa2au
03-20-2013, 04:42 AM
always start with the cheapest part first when replacing things on a whim

Agreed!

Mark rsa2au
03-21-2013, 08:18 AM
Fnally managed to figure out the diagnostic codes thanks to this site!
Code 22 - TPS reading abnormaly low:
new one on order
Code 34- sensor is reporting less air is entering the engine than makes sense based on RPM and TPS :
expect faulty TPS causing this.
Code 44 - indicates that the O2 sensor is showing a persistently high exhaust oxygen content (lean):
This boat has no O2 sensor and is running so rich it looks like a diesel..... might be TPS again.

Will see this week end when we replace parts.

JimN
03-21-2013, 09:37 AM
Fnally managed to figure out the diagnostic codes thanks to this site!
Code 22 - TPS reading abnormaly low:
new one on order
Code 34- sensor is reporting less air is entering the engine than makes sense based on RPM and TPS :
expect faulty TPS causing this.
Code 44 - indicates that the O2 sensor is showing a persistently high exhaust oxygen content (lean):
This boat has no O2 sensor and is running so rich it looks like a diesel..... might be TPS again.

Will see this week end when we replace parts.

The black smoke- does it smell like rubber, or unburned gas? Running lean doesn't produce black smoke. Also, a bad MAP shouldn't cause a TPS code- either the TPS is good, it's bad or the harness is faulty. To check the TPS or MAP sensors, you can/should check for 5VDC on the blue wire to each and measure the sensor's resistance across the other two pins. Also, measure the resistance from the black wire on each plug to the ground at the rear of the engine- if it's more than about .5 Ohms, find out why.

Your post indicates that you have a 2001 boat- I thought they added the O2 sensor after 2001 and I don't remember seeing one on the TBI when I went to training in Oct of 2000.

Before you replace a lot of parts and might not see results, make sure the grounds at the rear of the engine are clean and tight- the TPS and MAP sensors share their ground wire.

Also, make sure the two-wire engine coolant temperature sender (ECT) is operating properly.

If you want to "cheat" the ECM into thinking the engine is hot, go to Radio Shack and buy a pack of 100 Ohm resistors (buy a 5-pack- they're cheap). Remove the harness from the ECT (the two-wire ECT has one yellow wire and one black wire) and insert the ends of the resistor in the plug. You can do this while the engine is running and you should see a difference in how it runs- if you see no difference between running with the plug attached and unplugged but is clears up when you insert the resistor, it indicates that you need to check the sender. Substituting the resistor should ECM put the engine in RPM Reduction and if you try to increase RPM to >2000, it should run rough and it won't want to go much higher than 2000. You would then wire two or three resistors in series and insert the ends in the ECT plug- it it runs normally, the ECM and the rest of the sensors are OK, but the ECT is bad.

To test the ECT, it's best to remove it and measure the resistance, place it in hot water and measure the temperature with an IR thermometer or a confectioner's thermometer and refer to the temperature/resistance chart that's available online (or in a manual). If the resistance is high when the temperature is high/resistance is low when the temperature is low, the ECT is bad. If the black smoke doesn't stop when the engine warms up, I would suspect a bad ECT.

Here's the resistance range for a GM ECT-

In the Helm manuals there is a table:

degC degF Ohms
150 302 47
140 284 60
130 266 77
120 248 100
110 230 132
100 212 177
90 194 241
80 176 332
70 158 467
60 140 667
50 122 973
45 113 1188
40 104 1459
35 95 1802
30 86 2238
25 77 2796
20 68 3520
15 59 4450
10 50 5670
5 41 7280
0 32 9420
-5 23 12300
-10 14 16180
-15 5 21450
-20 -4 28680
-30 -22 52700
-40 -40 100700

mig
03-21-2013, 10:39 AM
Good info that would be hard (for me) to find elsewhere, thanks for the post.

The black smoke- does it smell like rubber, or unburned gas? Running lean doesn't produce black smoke. Also, a bad MAP shouldn't cause a TPS code- either the TPS is good, it's bad or the harness is faulty. To check the TPS or MAP sensors, you can/should check for 5VDC on the blue wire to each and measure the sensor's resistance across the other two pins. Also, measure the resistance from the black wire on each plug to the ground at the rear of the engine- if it's more than about .5 Ohms, find out why.

Your post indicates that you have a 2001 boat- I thought they added the O2 sensor after 2001 and I don't remember seeing one on the TBI when I went to training in Oct of 2000.

Before you replace a lot of parts and might not see results, make sure the grounds at the rear of the engine are clean and tight- the TPS and MAP sensors share their ground wire.

Also, make sure the two-wire engine coolant temperature sender (ECT) is operating properly.

If you want to "cheat" the ECM into thinking the engine is hot, go to Radio Shack and buy a pack of 100 Ohm resistors (buy a 5-pack- they're cheap). Remove the harness from the ECT (the two-wire ECT has one yellow wire and one black wire) and insert the ends of the resistor in the plug. You can do this while the engine is running and you should see a difference in how it runs- if you see no difference between running with the plug attached and unplugged but is clears up when you insert the resistor, it indicates that you need to check the sender. Substituting the resistor should ECM put the engine in RPM Reduction and if you try to increase RPM to >2000, it should run rough and it won't want to go much higher than 2000. You would then wire two or three resistors in series and insert the ends in the ECT plug- it it runs normally, the ECM and the rest of the sensors are OK, but the ECT is bad.

To test the ECT, it's best to remove it and measure the resistance, place it in hot water and measure the temperature with an IR thermometer or a confectioner's thermometer and refer to the temperature/resistance chart that's available online (or in a manual). If the resistance is high when the temperature is high/resistance is low when the temperature is low, the ECT is bad. If the black smoke doesn't stop when the engine warms up, I would suspect a bad ECT.

Here's the resistance range for a GM ECT-

In the Helm manuals there is a table:

degC degF Ohms
150 302 47
140 284 60
130 266 77
120 248 100
110 230 132
100 212 177
90 194 241
80 176 332
70 158 467
60 140 667
50 122 973
45 113 1188
40 104 1459
35 95 1802
30 86 2238
25 77 2796
20 68 3520
15 59 4450
10 50 5670
5 41 7280
0 32 9420
-5 23 12300
-10 14 16180
-15 5 21450
-20 -4 28680
-30 -22 52700
-40 -40 100700

Mark rsa2au
03-22-2013, 05:48 AM
Thanks JimN

The black Smoke is fuel, can smell it and see it on the water. New TPS ordered, and reconditioned injectors installed. Idle controll valve faulty and also on order. Replaced Maf sensor already. ECT seems fine but did not check exact resistance vs temp, but it did change with temp, will also check that.

Heading out to the boat tomorrow to replace parts, will check readings voltage etc before and after.

Cheers

Mark

Mark rsa2au
03-22-2013, 06:35 AM
Had the ECT available. Measured the resistance as below. Tested using steamer from my coffee machine, and the milk thermometer (dont tell SHMBO), reasonable accuracy I suppose.

The numbers seem to go in the right direction, and if the thermometer is out a little I am happy as this test shows that at opperating temp of 70degC/160F the resistance is about right at 320 which is lower than the 467 recommended. Therefore the ECM is getting the message that the engine is hot!

degC degF Ohms
90 194 241 - Mine = 198
80 176 332 - Mine = 234
70 158 467 - Mine = 320
60 140 667 - Mine = 480
50 122 973 - mine=730
40 104 1459 - Mine=1050
30 86 2238 - mine=1790

JimN
03-22-2013, 07:18 AM
Thanks JimN

The black Smoke is fuel, can smell it and see it on the water. New TPS ordered, and reconditioned injectors installed. Idle controll valve faulty and also on order. Replaced Maf sensor already. ECT seems fine but did not check exact resistance vs temp, but it did change with temp, will also check that.

Heading out to the boat tomorrow to replace parts, will check readings voltage etc before and after.

Cheers

Mark

How did you determine the parts being faulty? If you tested them, fine, but if you just started replacing parts in hopes of finding the solution, it's going to be an expensive, frustrating journey. Buy a manual- it has testing procedures for the various systems, each in their own section. If you know someone who has serviced GM engines, ask them for their help.

Did you check fuel pressure, yet? What's the voltage when it's running? These need to be at the correct voltage in order to operate properly.

Mark rsa2au
03-22-2013, 07:38 AM
Not big on waiting... have started testing.
Battery Voltage engine off - 12.7v. Engine on tested 13.5v ( I think) last week.

TPS;
Grey Wire to earth 5V,
Resistance to earth: 0.73
resistance across Blue to White pins on actual TPS Idle=2.16, WOT=6.19

MAP sensor:
Gray wire 5V
Resistance to earth 0.73
resistance from Black pin to Green pin 5.44

JimN: Read from other posts that manual is available and will order. Freight is more than book costs and 2 to 3 weeks wait.

I have heard of that mythical creature who knows how to maintain a GM V8 motor and who is not scared of it being in a boat... jokes aside yes I know a mechanic who will do it but again 2 to 3 weeks wait and expect huge $$$$. supply and demand :(

Rigged a tyre pressure guage to test fuel pressure, 25psi at idle but was leaking a little and I did not want too much fuel floating arround...... so I stopped.

Mark rsa2au
03-22-2013, 07:44 AM
How did you determine the parts being faulty? If you tested them, fine, but if you just started replacing parts in hopes of finding the solution, it's going to be an expensive, frustrating journey. Buy a manual- it has testing procedures for the various systems, each in their own section. If you know someone who has serviced GM engines, ask them for their help.

Did you check fuel pressure, yet? What's the voltage when it's running? These need to be at the correct voltage in order to operate properly.

JimN, thanks for your help so far! Testing parts now so trying to find fault before replacing parts. Know the idle motor is shot as it does no move with any power on or off. It stays closed permanently. The rest seem ok from the tests I have just done.

JimN
03-22-2013, 07:46 AM
Not big on waiting... have started testing.
Battery Voltage engine off - 12.7v. Engine on tested 13.5v ( I think) last week.

TPS;
Grey Wire to earth 5V,
Resistance to earth: 0.73
resistance across Blue to White pins on actual TPS Idle=2.16, WOT=6.19

MAP sensor:
Gray wire 5V
Resistance to earth 0.73
resistance from Black pin to Green pin 5.44

JimN: Read from other posts that manual is available and will order. Freight is more than book costs and 2 to 3 weeks wait.

I have heard of that mythical creature who knows how to maintain a GM V8 motor and who is not scared of it being in a boat... jokes aside yes I know a mechanic who will do it but again 2 to 3 weeks wait and expect huge $$$$. supply and demand :(

Rigged a tyre pressure guage to test fuel pressure, 25psi at idle but was leaking a little and I did not want too much fuel floating arround...... so I stopped.

How did you test the sensors? DON'T pierce the insulation on the wire. Use a stick pin and slide it into the green seal until it makes contact with the terminal, then test.

What is the idle speed of the engine? If the IAC is always closed, the RPM should be low, or it may not even idle at all. It definitely shouldn't idle well and may need the throttle to be opened just to keep it running. This may be the only real problem, although the fuel pressure is a bit low. Check the fuel filter and make sure it's clean. Your pressure should be in the 30 pound range at idle- the factory-recommended tests for fuel pressure are: Key ON/engine OFF, idle, 2000 RPM and WOT. Make notes of all test results and keep them as a baseline. Once it's running well, do all of the tests again, so you have something to compare to.

Use a fuel pressure gauge- these have a purge valve and you pcan use that to not only purge the air from the line, you can take a fuel sample (which I strongly recommend). If you know any auto mechanics, they should have one. Ply them with beer, if you have to.

Mark rsa2au
03-22-2013, 08:01 AM
Tested sensors with pin, then smeared dielectric grease over to help insulate.

Motor does idle but very lumpy, between 500rpm anf 800rpm. looking into the throttle body at idle it seems just enough air is getting through but the edges of the butterfly seem to get a fine line of white with ice and lumpy idle gets lower. One rev up and it clears the white ice ok.

WIll remove fuel filter and check, but will need a fuel pressure guage for safety.... will visit a bottle shop - for beer for mechanic!

High rev WOT still an issue with back firing / misfiring over 4100rpm. Changing to new plugs as previous plugs fouled from over fueling with faulty injectors - hope this works.

JimN
03-22-2013, 08:05 AM
Tested sensors with pin, then smeared dielectric grease over to help insulate.

Motor does idle but very lumpy, between 500rpm anf 800rpm. looking into the throttle body at idle it seems just enough air is getting through but the edges of the butterfly seem to get a fine line of white with ice and lumpy idle gets lower. One rev up and it clears the white ice ok.

WIll remove fuel filter and check, but will need a fuel pressure guage for safety.... will visit a bottle shop - for beer for mechanic!

High rev WOT still an issue with back firing / misfiring over 4100rpm. Changing to new plugs as previous plugs fouled from over fueling with faulty injectors - hope this works.

Did someone remove all of the plug wires at one time? Verify the firing order and base timing (you need to put the ECM in 'Diagnostic Mode" for this (you can use a paper clip, inserted in terminals A and B of the diagnostic harness plug, then raise RPM to 1000).

Mark rsa2au
03-22-2013, 08:37 AM
Did someone remove all of the plug wires at one time? Verify the firing order and base timing (you need to put the ECM in 'Diagnostic Mode" for this (you can use a paper clip, inserted in terminals A and B of the diagnostic harness plug, then raise RPM to 1000).

Thanks JimN, yes we have checked the firing order and the leads are correct. We have had to adjust the timing as per my first post to dial out the pinging low down but it brings the backfire / misfire lower down the rev to 4100, advance the timing increases the pinging but backfire and misfire higher up at 4500rpm.

Then just to be difficult some times it does not do it at all......:confused:

Fresh fuel as well!

Also read on other posts this week how to set base timing and will buy a timing light and test tomorrow.

Mark rsa2au
03-23-2013, 07:46 AM
Now I am stumped!!!:confused::confused::confused::confused: :confused:

Motor still running very rich, black smoke from exhausts and black sooty plugs from an hour on the water. Also backfiring over 4000rpm!! Dream boat not so much fun anymore:(:(

This is what we have done so far:
IAC broken unit replaced with new one - working perfectly.
Injectors reconditioned, all good. Also tested with New injectors - no change. New injectors had same flow rate as old injectors ( I wonder if old injectors were swaped for bigger flow units at some time)
Fuel pressure tested with dodgy fitting onto guage. Read 25psi before leaking so I think 30psi would be a safe bet.
ECT tested as above post, all good. Reading a little high but at least telling ECM it is HOT.
TPS tested as above post, all good. Replacement part no change.
Map sensor tested as above, all good. Replacement part makes no difference.
Plugs changed & gaped at 1.3 (from factory) will adjust down to 1.1 tomorrow but should not change issue above.
Distributer cleaned.
Timing checked as per manual and 10degree BTDC @1000rpm. ( floats a little on the timing light - not rock steady but easily visible).

What the hell else is these to check - service - replace to stop it running so rich and stop the backfiring?

JimN
03-23-2013, 08:32 AM
Now I am stumped!!!:confused::confused::confused::confused: :confused:

Motor still running very rich, black smoke from exhausts and black sooty plugs from an hour on the water. Also backfiring over 4000rpm!! Dream boat not so much fun anymore:(:(

This is what we have done so far:
IAC broken unit replaced with new one - working perfectly.
Injectors reconditioned, all good. Also tested with New injectors - no change. New injectors had same flow rate as old injectors ( I wonder if old injectors were swaped for bigger flow units at some time)
Fuel pressure tested with dodgy fitting onto guage. Read 25psi before leaking so I think 30psi would be a safe bet.
ECT tested as above post, all good. Reading a little high but at least telling ECM it is HOT.
TPS tested as above post, all good. Replacement part no change.
Map sensor tested as above, all good. Replacement part makes no difference.
Plugs changed & gaped at 1.3 (from factory) will adjust down to 1.1 tomorrow but should not change issue above.
Distributer cleaned.
Timing checked as per manual and 10degree BTDC @1000rpm. ( floats a little on the timing light - not rock steady but easily visible).

What the hell else is these to check - service - replace to stop it running so rich and stop the backfiring?

Have you checked the compression?

ECT- you mean the temperature gauge on the dash? That has nothing to do with what the ECM sees. The ECT you need to check has two wires and you need to check its resistance. If the resistance is high when the engine has been warmed up, it's bad.

The timing mark should be rock steady if the engine has been put in diagnostic mode. If it moves, it's either not in diagnostic mode or the shaft bushing may be worn.

How old are the cap, rotor and plug wires?

Mark rsa2au
03-23-2013, 09:01 AM
Have you checked the compression?

ECT- you mean the temperature gauge on the dash? That has nothing to do with what the ECM sees. The ECT you need to check has two wires and you need to check its resistance. If the resistance is high when the engine has been warmed up, it's bad.

The timing mark should be rock steady if the engine has been put in diagnostic mode. If it moves, it's either not in diagnostic mode or the shaft bushing may be worn.

How old are the cap, rotor and plug wires?

I pulled the correct temp sensor out (with the 2 wires) and tested resistance at 10deg C intervals up to 90degC and it was fine. A few ohms out from spec or the thermometer I was using was a little out, but either way it was registering HOT.

Engine was in Diagnostic mode at 1000rpm. How do I check the shaft bush, which shaft? the distributer shaft I assume?

Cap rotor and plug wires are origional - 270 hrs on a 2001 boat

thatsmrmastercraft
03-23-2013, 09:04 AM
I pulled the correct temp sensor out (with the 2 wires) and tested resistance at 10deg C intervals up to 90degC and it was fine. A few ohms out from spec or the thermometer I was using was a little out, but either way it was registering HOT.

Engine was in Diagnostic mode at 1000rpm. How do I check the shaft bush, which shaft? the distributer shaft I assume?

Cap rotor and plug wires are origional - 270 hrs on a 2001 boat

Cap and rotor definitely need to be replaced. I would replace the wires as well. You may be dealing with a simple cross-fire issue.

JimN
03-23-2013, 09:49 AM
I pulled the correct temp sensor out (with the 2 wires) and tested resistance at 10deg C intervals up to 90degC and it was fine. A few ohms out from spec or the thermometer I was using was a little out, but either way it was registering HOT.

Engine was in Diagnostic mode at 1000rpm. How do I check the shaft bush, which shaft? the distributer shaft I assume?

Cap rotor and plug wires are origional - 270 hrs on a 2001 boat

Can you run it at night or in total darkness? Your plug wires are old. The fact that they "only" have 270 hours is immaterial, they age, even though they're silicone. One thing that happens is, if the engine has been run hard at all, the conductor eventually loses conductivity at high frequencies, which means it may measure good with a multi-meter, but run like crap. A meter checks for DC resistance, but spark isn't DC voltage.

If you do run it in darkness, you may see arcing between the wires and this is likely to be part of the problem. Could be ALL of the problem. Caps can also develop carbon traces and if this happens, it may not be visible, but it has a bad effect on how the engine runs. It will be inside, not outside of the cap.

Mark rsa2au
03-23-2013, 06:14 PM
Contacts on the inside of the Distributer cap are corroded. I have sanded then back a little to remove this but there is still some surface pitting. Looks like the best option is to get a new one and new leads as well. I agree this might solve the misfire.

Do you think will solve the running rich? I have been researching injectors and cannot find out what mine are. No colour coding and the numbers on top do not come up with any search. What if the fuel pressure regulator was messed with previously? Should I unscrew the adjuster to lower some pressure in the injectors? Or would a pressure gauge show this up at the shrader valve?

JimN
03-23-2013, 06:37 PM
Contacts on the inside of the Distributer cap are corroded. I have sanded then back a little to remove this but there is still some surface pitting. Looks like the best option is to get a new one and new leads as well. I agree this might solve the misfire.

Do you think will solve the running rich? I have been researching injectors and cannot find out what mine are. No colour coding and the numbers on top do not come up with any search. What if the fuel pressure regulator was messed with previously? Should I unscrew the adjuster to lower some pressure in the injectors? Or would a pressure gauge show this up at the shrader valve?

Never mess with a factory-adjusted part. That's set under controlled conditions, which we don't have. If the pressure is too low, the fuel won't atomize as well as it should and that means some cylinders will get more than enough, some the right amount and some won't get enough. Running hard and having some cylinders too lean will burn the valves and probably the piston, possibly scoring the cylinder(s). There's no way to "un-mess with" the regulator. If you think/know it was messed with, replace it. Also, leave the idle stop alone. This isn't like a carb- there's really nothing to adjust in the field. If you have correct compression, spark timing/intensity and fuel/air delivery, a sensor problem is the next most likely problem. Since you have replaced most of them, it's unlikely that you replaced a bad sensor with another bad one.

This doesn't leave many things to look at, but I did recommend measuring resistance from the sensors to the battery negatives and the ground at the back of the engine. If your ground is bad, it can run exactly as you described. It's too bad nobody in Australia has taken it upon themselves to buy the necessary diagnostic equipment for these, although I don't know how many ski and wakeboard boats are over there.

Mark rsa2au
03-29-2013, 05:16 AM
Ok Still stumped:huh::huh:.... Engine has a huge misfire / backfire at anything above 4100rpm, and on occasion limits revs to 2500 - shut down restart and rev limit gone:eek:.
Today had Code 22 (TPS reading low) and 44 (O2 sensor reading lean but this boat has no O2 sensor).

So far have replaced the Idle motor, the TPS, the MAP sensor, the Spark plugs, the spark leads, distributer & rotor. Tested Temp sensor ok, fresh fuel, New injectors. Also timing 10deg BTDC @1000rpm in diagnostic mode. Fuel pressure arround 29 - 31psi.

Checked earth from sensors to ECM and all good, but earth wire at sensors to rear earth connection shows 0.7 - 1.1 ohms difference. Is this ok and if not what would cause it?

Checked water pump, trans cooler, and calibrated temp sensor for the engine warning light. The check light comes on and goes off when I dissconnect this temp sensor. Calibrated to 95degrees C (203F) and it comes on after a hard run but the dash temp shows 160F and this sender is in the same water channel is it not?

JimN there are many Mastercrafts (also Malibu- made locally, Nautique, Supra, Mobius,etc) over here, its just the dealer will not support boats not imported by them - even though this boat was imported before 2004 when MC officialy started in OZ.

Not sure where to go next.... any suggestions other then a match?:(

SkiDaddy
03-29-2013, 07:34 AM
You might want to check out automotive internet forums for vehicles that use the same engine as yours and then search those sites for similar problems. Maybe something like www.chevroletforums.com and there are a bunch of others.

Aside from you checking the fuel pressure with the dodgy gauge, have you done anything else with the fuel system? To me it seems like you've kind of ignored the fuel system so far. I think that some of the 5.7L Vortec engines needed around 50-60 psi for fuel pressure.....are you 100% sure that 30 psi is what this engine needs? I don't know the answer, just throwing out some ideas.

Cheers & good luck!

JimN
03-29-2013, 08:51 AM
Ok Still stumped:huh::huh:.... Engine has a huge misfire / backfire at anything above 4100rpm, and on occasion limits revs to 2500 - shut down restart and rev limit gone:eek:.
Today had Code 22 (TPS reading low) and 44 (O2 sensor reading lean but this boat has no O2 sensor).

So far have replaced the Idle motor, the TPS, the MAP sensor, the Spark plugs, the spark leads, distributer & rotor. Tested Temp sensor ok, fresh fuel, New injectors. Also timing 10deg BTDC @1000rpm in diagnostic mode. Fuel pressure arround 29 - 31psi.

Checked earth from sensors to ECM and all good, but earth wire at sensors to rear earth connection shows 0.7 - 1.1 ohms difference. Is this ok and if not what would cause it?

Checked water pump, trans cooler, and calibrated temp sensor for the engine warning light. The check light comes on and goes off when I dissconnect this temp sensor. Calibrated to 95degrees C (203F) and it comes on after a hard run but the dash temp shows 160F and this sender is in the same water channel is it not?

JimN there are many Mastercrafts (also Malibu- made locally, Nautique, Supra, Mobius,etc) over here, its just the dealer will not support boats not imported by them - even though this boat was imported before 2004 when MC officialy started in OZ.

Not sure where to go next.... any suggestions other then a match?:(

The 1.1 Ohms is high. Get the resistors and substitute them for the ECT, as I posted. If the check engine light goes off when you disconnect it, it has a problem (or, the plug/wires on its harness). The sensor going to the gauge has nothing to do with what's going to the ECM.

44 may be IC module- contact Mastercraft or Indmar and ask them about it- my manual isn't here at the moment, so I can't check this.

Disconnect the battery, let it sit for a few minutes and remove the plugs from the ECM. Open the plastic shell and look for the black wires and measure from the ECM plug to the battery posts, not the terminals. The resistance between the terminal and post can be enough to cause problems.

Here's a manual for MEFI 4, but it's not exactly for your engine. The pin out,, diagrams and diagnostics are basically the same. You'll notice that the MAP sensor is different (the one in the link is like the one on the LTR. MCX and some of the others that aren't TBI).

http://www.pirate4x4.com/tech/billavista/MEFI/MEFI%204%20&%204B%20DIAGNOSTIC%20MANUAL%20%28L510005P%29.pdf

Mark rsa2au
04-01-2013, 12:45 AM
You might want to check out automotive internet forums for vehicles that use the same engine as yours and then search those sites for similar problems. Maybe something like www.chevroletforums.com and there are a bunch of others.

Aside from you checking the fuel pressure with the dodgy gauge, have you done anything else with the fuel system? To me it seems like you've kind of ignored the fuel system so far. I think that some of the 5.7L Vortec engines needed around 50-60 psi for fuel pressure.....are you 100% sure that 30 psi is what this engine needs? I don't know the answer, just throwing out some ideas.

Cheers & good luck!

Thanks Mate, I have been looking at the other forums for similar issues, some have been helpfull, most not because it seems the issue might be specific to the Indmar electrics.

The workshop manual states 30 PSI for fuel which is what we are measuring. We have also used both the origional and the new injectors with no change. Dismantled and checked fuel pressure regulator - seems fine. Fuel lines not kinked and pressure ok with neither set of injectors changing the issue means we crossed this one off the list.

Mark rsa2au
04-01-2013, 12:55 AM
The 1.1 Ohms is high. Get the resistors and substitute them for the ECT, as I posted. If the check engine light goes off when you disconnect it, it has a problem (or, the plug/wires on its harness). The sensor going to the gauge has nothing to do with what's going to the ECM.

44 may be IC module- contact Mastercraft or Indmar and ask them about it- my manual isn't here at the moment, so I can't check this.

Disconnect the battery, let it sit for a few minutes and remove the plugs from the ECM. Open the plastic shell and look for the black wires and measure from the ECM plug to the battery posts, not the terminals. The resistance between the terminal and post can be enough to cause problems.

Here's a manual for MEFI 4, but it's not exactly for your engine. The pin out,, diagrams and diagnostics are basically the same. You'll notice that the MAP sensor is different (the one in the link is like the one on the LTR. MCX and some of the others that aren't TBI).

http://www.pirate4x4.com/tech/billavista/MEFI/MEFI%204%20&%204B%20DIAGNOSTIC%20MANUAL%20%28L510005P%29.pdf

Thanks JimN,

I now have the boat parked for a while, hit a rock in 7 feet of water....... buggered the prop, shaft, strut, and log....:(
Then found the fiberglass repair on the exhaust had blown off with one of the backfires and had filled the bilge..... because the auto function of the bilge pump is not working.:mad:

Will check the earth resistance etc when I feel like looking at it again.

On the bright side the over fueling and running rich seems to have stopped.

1redTA
04-01-2013, 10:29 AM
That is terrible!

Mark rsa2au
07-14-2013, 04:57 AM
Wish I could post pictures... Pulled out the carter fuel pump assembly and replaced what was left of the old fuel filter. Had started to disintegrate and pieces were stuck in the pump inlet screen. Only about 50% of the screen clear for fuel to flow.:confused:

I think this might be why the motor is missing at high rpm and high loads.... :woohoo:

Have also replaced Temp Sensor and as per seperate post, found loads of Muck stuck arround hole where the temp sensor fits. Now new temp sensor, clear to have maximum water flow should solve over heat issue with computer reducing RPM to 2000.

Yet to get it out on the water... way too cold down under, but will try next weekend.

Mark rsa2au
07-14-2013, 07:47 AM
97708
This is the pump inlet screen!

Mark rsa2au
07-14-2013, 07:49 AM
97709
The old filter:(
97710
Note the corrosion on the metal frame:confused:

JimN
07-14-2013, 09:33 AM
Wish I could post pictures... Pulled out the carter fuel pump assembly and replaced what was left of the old fuel filter. Had started to disintegrate and pieces were stuck in the pump inlet screen. Only about 50% of the screen clear for fuel to flow.:confused:

I think this might be why the motor is missing at high rpm and high loads.... :woohoo:

Have also replaced Temp Sensor and as per seperate post, found loads of Muck stuck arround hole where the temp sensor fits. Now new temp sensor, clear to have maximum water flow should solve over heat issue with computer reducing RPM to 2000.

Yet to get it out on the water... way too cold down under, but will try next weekend.

Who has maintained/serviced this boat since it was new? If the fuel pump/filter was that bad, it's because the scheduled maintenance wasn't performed and the interval information IS available, so there's really no good reason for this.

JimN
07-14-2013, 09:41 AM
97709
The old filter:(
97710
Note the corrosion on the metal frame:confused:

What additives are in your gas when you buy it at the pump? Whatever it has, it's attracting a lot of water and I think it's amazing that the pump lasted as long as it did. I would recommend taking a fuel sample before running it again. If you find water, remove it from the gas. If you see a milky layer in the gas, remove ALL of the gas- this milky layer is due to "phase separation" and not only does it not burn well, it doesn't pass through the filter as well as clean gas (assuming the 5 micron filter element is on the pump).

Mark rsa2au
07-15-2013, 05:44 AM
What additives are in your gas when you buy it at the pump? Whatever it has, it's attracting a lot of water and I think it's amazing that the pump lasted as long as it did. I would recommend taking a fuel sample before running it again. If you find water, remove it from the gas. If you see a milky layer in the gas, remove ALL of the gas- this milky layer is due to "phase separation" and not only does it not burn well, it doesn't pass through the filter as well as clean gas (assuming the 5 micron filter element is on the pump).

JimN, I think the boat sat arround for a few years with an empty tank. The fuel here in Australia does not contain any "Special" additives that I know of, and I stay away from the ethanol blends.

I have pushed a number tanks through the motor so far (at its worst I was going through 2 tanks a day) and looking at the fuel in the tank it was crystal clear all the way to the bottom. There was what looked like sand (rust flakes) on the bottom and I syphoned these off from the open hole. I have also pumped a few bottles of fuel system cleaner through over various fills so hopefully there is no residue left. New filter, cleaned and checked pump, strainer clear, and we are good to go.

On the subject of scheduled maintainence I doubt much was done over the last few years, but it all looks good with no rust, nothing broken, and other than finding the causes of the above issues seems ok. Pulls like a freight train, and when running properly is as smooth as silk.

I am getting there.. Persistance beats resistance! Now all I need is above freezing temps to give it a test run... know any weather gods?

JimN
07-15-2013, 06:07 AM
JimN, I think the boat sat arround for a few years with an empty tank. The fuel here in Australia does not contain any "Special" additives that I know of, and I stay away from the ethanol blends.

I have pushed a number tanks through the motor so far (at its worst I was going through 2 tanks a day) and looking at the fuel in the tank it was crystal clear all the way to the bottom. There was what looked like sand (rust flakes) on the bottom and I syphoned these off from the open hole. I have also pumped a few bottles of fuel system cleaner through over various fills so hopefully there is no residue left. New filter, cleaned and checked pump, strainer clear, and we are good to go.

On the subject of scheduled maintainence I doubt much was done over the last few years, but it all looks good with no rust, nothing broken, and other than finding the causes of the above issues seems ok. Pulls like a freight train, and when running properly is as smooth as silk.

I am getting there.. Persistance beats resistance! Now all I need is above freezing temps to give it a test run... know any weather gods?

If you and/or the boat are very close to the ocean, the rust could be from brackish/salt water. Hard to say without having been there. Good to see that it's running well.