5.0L EFI Question

[alldodge]

The motors use the same Delphi ECU as the GM truck/autos but they are not programed the same. You cannot put one off a truck and have it work on the boat.

Its very unusual for both ECU to do the same thing. They both supply spark but have no ground pulses going to the injectors. There is 12V on the Pink wires and while the engine cranks the Blue or Green wires on the other side of the injectors do not pulse to ground?

The next thing is get a paper clip and a 12V resistor and see what the ECU shows for codes

 

[Rickochet]

They both supply spark but have no ground pulses going to the injectors. There is 12V on the Pink wires and while the engine cranks the Blue or Green wires on the other side of the injectors do not pulse to ground?

The next thing is get a paper clip and a 12V resistor and see what the ECU shows for codes

Thanks for the info. Will pass this along to my bud the mechanic. He and the boat are 90 miles away. He put his noid lights on the injectors and none light up. Does this mean neither of blue or green wires are pulsing to ground?

 

[alldodge]

Maybe, depends on how it was connected. Noid lights are LED's and have a + and - side. In any case, the Pink wires should have a constant 12V when key is ON.

 

[Rickochet]

Haven't heard back from the mechanic yet. Understandable since he is 65 and does dialysis three days per week and has other major health issues. I am soon to be 68 with bad knees and back so I can't do much. I have checked with every Mercruiser dealer in the area and nobody will do field work. Mercruiser support was zero help. Not sure where to go at this point. Best I could find is the OEM ECM is part # 861925T3 but was replaced by 892799A01. If I could find a used one to test that would be great but I don't see any. I only found one vendor that had new ECM's and they wanted $1,699 each and were non-returnable. Not knowing if it is indeed bad ECM's I am not blowing $3,400 on unknowns. This is really frustrating and disheartening. After 32 years of houseboating we made a tough decision to retire from boating do to health considerations and decided to put the boat up for sale. The boat is not very marketable without running motors. I had hoped the low hours on the motors (49 hours) would be a good selling point.

 

[Fun Times]

Sounds like you're getting close to the point of needing to mail your 2 ECM's off for testing and possibly repair if possible. Bob would be the guy to send them out to and hope for the best.... http://mefiburn.com/ecmrepair.asp

Before you do though, you might want to try a few things first such as testing your injectors to see if they seem to be activating, https://www.youtube.com/watch?v=pyz5qx0N6Sk , https://www.youtube.com/watch?v=mQ9Yhj8pSfo

Also try searching online videos of How To Clean Fuel Injectors for an understanding. You want to know if the injector will flow fuel through them and not clogged up from sitting.

It's slightly possible that the ignition control module under the distributor cap is bad on the side that communicates with the ECM to pulse the fuel injectors but yet still allow the coil to fire.... For a lower cost alternative, you can find new modules at the local auto store as they are the same. Just search a 1994ish 5.7 GM truck TBI engine. Probably be in the $50.00 or under range depending on where you look. http://www.autozone.com/ignition-tu...ng=search&isIgnoreVehicle=false&model=control

^ EBay is way cheaper but you get what you pay too. Just send the parts to his house.

Though the following link is an automotive dialogue and not 100 % the same wiring colors, etc. as your marine engine, Your tech helping you may want to read the following diagnostics test for a good brush up on the GM ignition control module system as it's a good one to read for general purposes regarding the same ICM system you have in your boat.
http://easyautodiagnostics.com/gm/4.3L-5.0L-5.7L/distributor-mounted-icm-tests-1

Now that you have a new fuel pump, do you hear/feel the fuel pump turn on for 2 - 3 seconds as soon as you turn the ignition key to on??
Also does the fuel pump turn on when cranking over the engine??

Yes a lightning strike could damage the ECMs.

Does your service guy have a marine EFI scan tool to check codes? If not, show him this video as it helps refer back to post number 21 above from AD, https://www.youtube.com/watch?v=fSEwwa6D2jM

 

[Rickochet]

Sounds like you're getting close to the point of needing to mail your 2 ECM's off for testing and possibly repair if possible. Bob would be the guy to send them out to and hope for the best.... http://mefiburn.com/ecmrepair.asp

I found them when looking for replacement ECM's. Didn't realize they can check and repair them as well. Good info thanks.

Now that you have a new fuel pump, do you hear/feel the fuel pump turn on for 2 - 3 seconds as soon as you turn the ignition key to on??
Also does the fuel pump turn on when cranking over the engine??

Boat is 90 miles away. My bud told me the fuel pumps work and fuel is getting to the throttle body. He says you can actually hear them when running.

Does your service guy have a marine EFI scan tool to check codes? If not, show him this video as it helps refer back to post number 21 above from AD, https://www.youtube.com/watch?v=fSEwwa6D2jM

I don't think he has a scan tool. I passed along the video link. Is there a link to show what the codes mean?

Thanks for taking time to post the above information. Having a source to get the ECM's checked if needed is a big help.

 

[Rickochet]

Haven't heard anything from my bud the mechanic but hoping to get to the lake this weekend. Just a couple of questions. Is there a way to check to see if the ignition control modules in the distributor to see it they are sending signal to the ECM? Also, will have him check the pink wire to the injectors to see if it is getting 12v with key on. If getting signal from distributor and 12v to pink wire, what next? Time to ship off the ECM's for testing?

 

[alldodge]

Is there a way to check to see if the ignition control modules in the distributor to see it they are sending signal to the ECM?

Your getting spark (able to put fuel in the TB and it fires) so the ECM is working. What your not getting is fuel

Also, will have him check the pink wire to the injectors to see if it is getting 12v with key on. If getting signal from distributor and 12v to pink wire, what next?

See if the ground is being applied to the other wires (Blue and Green) by the ECM. This can be done by placing the noid across the injector contacts and see if it goes ON/OFF.

Time to ship off the ECM's for testing?

That would be my next thought

 

[Rickochet]

Your getting spark (able to put fuel in the TB and it fires) so the ECM is working. What your not getting is fuel

Agreed, no fuel. I seem to getting mixed info. You say if plugs are getting fire the ECM is working. Other posts suggest plugs can get spark but ECM not getting signal from the distributor. I saw this posted on another thread for the 5.7 EFI and changing the distributor module fixed that one. It also fired was gas poured in TB but injectors were not pulsing.

See if the ground is being applied to the other wires (Blue and Green) by the ECM. This can be done by placing the noid across the injector contacts and see if it goes ON/OFF.

I think he did this before changing the fuel pumps. Noid light not flashing (assumed he had lights hooked up correctly). Can you check this with a DVM touching the pink and blue or green wires while cranking or is the DVM to slow to respond?

 

[Rickochet]

Maybe, depends on how it was connected. Noid lights are LED's and have a + and - side. In any case, the Pink wires should have a constant 12V when key is ON.

Do you have a link for the full wiring diagram. I am curious to see where the pink wire originates. I have tried a search for wiring diagrams with no luck.

 

[alldodge]

Agreed, no fuel. I seem to getting mixed info. You say if plugs are getting fire the ECM is working. Other posts suggest plugs can get spark but ECM not getting signal from the distributor. I saw this posted on another thread for the 5.7 EFI and changing the distributor module fixed that one. It also fired was gas poured in TB but injectors were not pulsing.

Would have to see the post which this was the issue. Your motor has an TBV distributor and MEFI-3 ECM, if the other post was discussing an HVS distributer. FT mentioned that the module in the distributer may be the issue, and he has posted links to test and or replace.

I think he did this before changing the fuel pumps. Noid light not flashing (assumed he had lights hooked up correctly). Can you check this with a DVM touching the pink and blue or green wires while cranking or is the DVM to slow to respond?

Your not going to get much of reading with a voltmeter because meters are slow to react.

FT also posted how to test the injectors

 

[alldodge]

The one above shows the pink goes to the fuse. This is the whole thing but will probably be hard to read

 

[boatguya1]

I just a couple days ago saw a small block that would run on starting fluid so customer assumed spark ok. Noid light showed no injector pulse. I checked with kva meter for spark and got nothing, checked with spark gap tester and got nothing. Scratching my head I shot some starting fluid at it and it tried to run. I went up to the helm and cranked it again, no tach movement. I did the TBV ignition sensor test and got spark when grounding the white/green wire. I put in a sensor I use to confirm diagnosis and she started right up.

I assume the sensor was working just enough to get enough juice in the coil to barely spark, Evidently enough to light either but not enough to ignite fuel and also not enough for the ECM to see the motor spin and turn on the injectors.

Jim Frye (Former Merc instructor) says "put the eyedometer on the tachometer" while cranking it should move, if not look for why not.

James

 

[Fun Times]

If you happen to have an AutoZone nearby, it was mentioned they can test this style ICM as they may have an module tester. There are special tools to test modules that one could buy too. Though the module shown in the following link isn't the same exact shape or mounting design as yours, the ICM works just about the same way as yours and is a good topic of how the module works internally. http://chevythunder.com/hei_troubles...ge_2_coil_.htm

My thought (theory) for yours and possibly boatguya1 would be only one half of the Ignition Control Module was/is working as in theory it's kind of a two part system. One side fires the ignition coil (spark) while the other side tells the ECM hey now wake up because the engine is turning over right now. Then the ECM says okay I'll start pulsing the fuel injectors. If the pulsing side stops working you'll get no fuel but the spark is there...Hand poor some gas/starting fluid the engine would try to start.

Confusing i know as normal thought is the ICM works or it don't but this system is a just a bit different so the theory is probable. Since you have two engines not working you could try buying one ICM, try it out...If it don't work, keep it as a spare onboard because there will be a day you need to install a new one anyways as they do eventually fail.

Boatguy, Do you know if Jim is still in the Hayward Ca area? Retired now?? ... It's been many years since I last saw him.

 

[Rickochet]

If you happen to have an AutoZone nearby, it was mentioned they can test this style ICM as they may have an module tester. There are special tools to test modules that one could buy too. Though the module shown in the following link isn't the same exact shape or mounting design as yours, the ICM works just about the same way as yours and is a good topic of how the module works internally. http://chevythunder.com/hei_troubles...ge_2_coil_.htm

My thought (theory) for yours and possibly boatguya1 would be only one half of the Ignition Control Module was/is working as in theory it's kind of a two part system. One side fires the ignition coil (spark) while the other side tells the ECM hey now wake up because the engine is turning over right now. Then the ECM says okay I'll start pulsing the fuel injectors. If the pulsing side stops working you'll get no fuel but the spark is there...Hand poor some gas/starting fluid the engine would try to start.

Confusing i know as normal thought is the ICM works or it don't but this system is a just a bit different so the theory is probable. Since you have two engines not working you could try buying one ICM, try it out...If it don't work, keep it as a spare onboard because there will be a day you need to install a new one anyways as they do eventually fail.

Boatguy, Do you know if Jim is still in the Hayward Ca area? Retired now?? ... It's been many years since I last saw him.

Getting a new ICM sounds like a good idea. It would appear that the ICM for my boat is one like this, Merc #87-892150Q02 http://www.ebay.com/itm/like/3225916...=ps&dispItem=1. Maybe I misunderstood, but I thought I read previously that a local auto parts store might have a GM drop in replacement. I am not finding any GM ICM's that look like the Merc one.

Also, doing some searching, when adding in the motor model # 4M32027N1 which is on my manual is shows the non Thunderbolt distributor with an external ignition module like this one https://www.amazon.com/Sierra-International-18-5107-1-Ignition-Module/dp/B000N9ZIYQ

 

[Fun Times]

Getting a new ICM sounds like a good idea. It would appear that the ICM for my boat is one like this, Merc #87-892150Q02 http://www.ebay.com/itm/like/3225916...=ps&dispItem=1. Maybe I misunderstood, but I thought I read previously that a local auto parts store might have a GM drop in replacement. I am not finding any GM ICM's that look like the Merc one.

Also, doing some searching, when adding in the motor model # 4M32027N1 which is on my manual is shows the non Thunderbolt distributor.

Interesting...I see where you're getting that info but not sure why and who's right and who's wrong....Yet....

Using (auto searching) your serial number (0M069225) you posted showed me the type of ICM you had so I went off that info to say all the things I said to do/try knowing the system. Your model number is correct using 4M32027N1.

The distributor model/design I first looked up uses a GM style ICM by auto search.... The model number shows the Mercruiser distributor sensor which works sort of different than the GM design. You will need to look at your boats distributor and see what design you really have.

Here is a few sites that says (said) you have the GM style ICM which will be item number 9,
http://www.mercruiserparts.com/bam/subassembly/31844/2704/70
https://www.perfprotech.com/mercury...tion-components/assembly/2704/70?umodel=12340
http://www.marineengine.com/parts/mercury_marine_parts/sn/0M069225/4M32027N1/2704_70 < This link will be dead to you but it shows the same design as the 2 above.

Here using the model number shows the Mercruiser distributor sensor like you found, http://www.crowleymarine.com/mercury-outboard/parts/4856_80.cfm?mdl=MPIAZB

Though they're dead links again, one site shows both designs under the model number.
DISTRIBUTOR AND IGNITION COMPONENTS FOR MERCRUISER 5.0L EFI ALPHA/BRAVO 5.7L EFI ALPHA/BRAVO (GEN +) ENGINE (GM Design)
Distributor And Ignition Components FOR MERCRUISER 5.0L EFI ALPHA/BRAVO 5.7L EFI ALPHA/BRAVO (GEN +) ENGINE (Mercruiser Design)

Edit: Now after all that, I see it now, your serial number range finder vs auto search number look up shows the Mercruiser design distributor sensor like you found and should be the most accurate, http://www.mercruiserparts.com/bam/subassembly/31846/4856/80

That being the case of you having the Mercruiser type sensor, it's more probable to be an ECM issue now.
Sorry about all the confusion.

The Mercruiser sensor is Mercruiser specific and not available in most auto stores with the exception form a store like NAPA which sells some sierra marine aftermarket parts which should be sierra part number 18-5116-1. https://www.napaonline.com/en/p/SME1851161

 

[Rickochet]

Edit: Now after all that, I see it now, your serial number range finder vs auto search number look up shows the Mercruiser design distributor sensor like you found and should be the most accurate, http://www.mercruiserparts.com/bam/s.../31846/4856/80

That being the case of you having the Mercruiser type sensor, it's more probable to be an ECM issue now.
Sorry about all the confusion.

The Mercruiser sensor is Mercruiser specific and not available in most auto stores with the exception form a store like NAPA which sells some sierra marine aftermarket parts which should be sierra part number 18-5116-1. https://www.napaonline.com/en/p/SME1851161

Looks, like I have the Mercruiser type. I sent my bud a pic and he confirmed that is the one. Too bad since he had one in stock. Will check the ECU codes next time at the lake and will probably ship them off for testing.

Thank you everyone for taking time to reply.

 

[Rickochet]

I just a couple days ago saw a small block that would run on starting fluid so customer assumed spark ok. Noid light showed no injector pulse. I checked with kva meter for spark and got nothing, checked with spark gap tester and got nothing. Scratching my head I shot some starting fluid at it and it tried to run. I went up to the helm and cranked it again, no tach movement. I did the TBV ignition sensor test and got spark when grounding the white/green wire. I put in a sensor I use to confirm diagnosis and she started right up.

I assume the sensor was working just enough to get enough juice in the coil to barely spark, Evidently enough to light either but not enough to ignite fuel and also not enough for the ECM to see the motor spin and turn on the injectors.

Jim Frye (Former Merc instructor) says "put the eyedometer on the tachometer" while cranking it should move, if not look for why not.

James

Just curious, but was this the Merc sensor or the GM type?

 

[boatguya1]

It was the Mercruiser thunderblt V distributor and it is the sensor in the distributor that was replaced to fix the problem. 892150Q02 merc part number for this sensor. I've been doing this since 92 and had never seen one do this til now. It's the sensor the "teeth" on the rotor pass through. Try a spark gap tester to see if getting good spark.

Fun Times I don't know if Jim is still in the Hayward area, Merc. closed the school there. He is a good guy, hope he is still with Mercury.

 

[boatguya1]

View attachment 495642=12201-Troubleshooting.pdf

If no spark with spark gap tester follow this troubleshooting tree.