2000 Mercruiser 5.0L EFI stalls when warm/hot

[Usspikes]

I have a 2000 mercruiser 5.0 EFI installed in a 2000 Searay 120BR. Ignition is Thunderbolt V. I'm the original owner, engine is completely stock. 2 years ago I had a Vapor Lock issue which was rectified by installing the mercruiser check valve in the cooling system between the fuel cooler and thermostat housing. I have not had any other problems or issues with the motor. I had a dual battery setup installed with Off-1-Both-2 battery switch using Optima Blue Top batteries during the winter by a local marine center.

Memorial Day weekend engine ran great, no issues all weekend. Took a 45 mile ride plus pulled skiers/tubers all weekend.

Week of the 4th of July launched boat and drove approx. 2 miles to dock. Approx. 2 hours later I started the engine to take tubers out. Engine started and idled fine. All gauges were reading normal. After approx. 5 minutes RPM fluctuated between 400 - 1000 with associated engine surging for a second or two then engine died. Engine would start for a second or two and then die again. I disconnected the fuel line at the Throttle Body and turned the key to run. I got the normal 2 beeps heard the fuel pump relay click and pump ran for the required 2 seconds but no fuel came out of fuel feed line. Thought i had a bad fuel pump so i replaced it and the cooler as it comes as a kit. Fuel pressure regulator did not come with kit so it is the original. Without going into great detail, I've eliminated the fuel system as a cause.

Took boat out last weekend took approx 5 mile ride and pulled a skier. While switching skiers engine at idle I got the same stalling condition as discribed earlier. The coil felt hot, but I'm not sure how hot it should be. I pulled the coil wire off the coil and the connector was still in the coil. I installed a new coil wire and took boat out and ran it hard for about a half hour. After being back a dock for a few minutes engine started, ran for a few minutes then same stalling condition. Once engine cools it starts and runs fine for a while then same thing occurs.

I'm petty sure my issue is electrical. When engine won't start I pulled the coil wire of the coil and while cranking engine I get spark arc between coil wire and coil, but I'm not sure how intense the spark arc should be. Thinking I might have a intermittent short, I have wiggled a shook the engine wiring harness all over paying particular attention to areas of the harness near sensor connection points but I have not gotten the engine to stall or even hesitate. Once the engine gets hot, same thing all over again. I've checked all connections to ensure they a tight and no corrosion was present.

Failure doesn't occur after a specific amount of engine run time as the failure occurs after various amounts time running.

I believe heat and electrical are the primary causal factors.

Anyone have any ideas?

Sorry this is so long, but I want to get all the facts in.

 

[alldodge]

Re: 2000 Mercruiser 5.0L EFI stalls when warm/hot

Welcome to the forum

To check the ignition system run the troubleshooting guide in this link
http://www.google.com/url?sa=t&rct=...=pcMDjhgxy9TJqrVQpf3Vnw&bvm=bv.49784469,d.aWc

It starts on page 22 but the rest of the doc should help

 

[spdracr39]

Re: 2000 Mercruiser 5.0L EFI stalls when warm/hot

My vapor lock issue would show 0 fuel pressure on the rail when it was acting up. None of the cheap fixes worked for me so I had to install a boost pump kit to make it start back when it was hot. It does not really sound exactly like mine when this was occurring so it could be electrical. Check that rail pressure to see.

 

[Usspikes]

Re: 2000 Mercruiser 5.0L EFI stalls when warm/hot

My local marine repair center has been unable to duplicate my problem. No codes stored in ECM. They suggest replacing the Ignition Control Sensor in the distributor.

Anyone hear of or experience the sensor failing only when hot?

 

[alldodge]

Re: 2000 Mercruiser 5.0L EFI stalls when warm/hot

It is possiable but have not heared of one. I would suspect the coil before the sensor

 

[Usspikes]

Re: 2000 Mercruiser 5.0L EFI stalls when warm/hot

Alldodge,
I'm going to make sure they test the ignition system before just arbitrarily changing a part.

 

[Jesse Walter]

Re: 2000 Mercruiser 5.0L EFI stalls when warm/hot

You may look into replacing your Idle Air Control. (AIC). You can find them on Ebay for around $90. Usually you get 2 warning beeps when its bad but maybe you aren't getting that for some reason. Usually the engine will run great at higher RPMs but dies at idle when these go bad. Maybe something to check....

Jesse

 

[Usspikes]

Re: 2000 Mercruiser 5.0L EFI stalls when warm/hot

Jesse,
Thanks for the advice. I checked the IAC. It's good. I haven't been able to check the entire ignition system yet when it is is failure mode as I didn't have a spark tester handy. I did notice that when it won't start the fuel injectors are just spitting fuel. After looking at a wire schematic, I see the white/red wire from the ignition sensor in the distributor connects to the purple wire going to the throttle body and fuel pump relay. Can anyone tell me how the ignition sensor controls fuel pump operation?

 

[alldodge]

Re: 2000 Mercruiser 5.0L EFI stalls when warm/hot

During start mode the pulses from the distributor are read by the ECM
When the ignition switch is turned to the crank position, the ECM turns ON the fuel pump relay and the fuel pump builds up pressure. The ECM then checks the Engine Coolant Temperature (ECT) sensor and Throttle Position (TP) sensor and determines the proper air/fuel ratio for starting. The ECM controls the amount of fuel delivered in the starting mode by changing how long the injectors are turned ON and OFF. This is done by pulsing the injectors for very short times (spitting fuel).

 

[Usspikes]

Re: 2000 Mercruiser 5.0L EFI stalls when warm/hot

Thanks Senior,
Now I understand how the logic works. I believe I'm on the right track with the sensor. I didn't have a spark tester, but when I disconnect the coil wire from the coil and hold it about 1/2" from the coil spark does arc between the wire and coil so I know the distributor juice. I know what you mean about the injectors pulsing. When no in failure mode they pulse in a nice cone shaped Pattern. When in failure mode the pulses are more like a dribble. (Lack of fuel pressure)

BTW I'm also a SCPO, retired 2009.

Thanks for the help brother

 

[alldodge]

Re: 2000 Mercruiser 5.0L EFI stalls when warm/hot

BTW I'm also a SCPO, retired 2009.

Looks like your going to get to the bottom of it. The CPO is what you get here at iboats after you post I think 700 times. I was in the Coast Guard and didn't make it that high. Thank you for your service

Bob

 

[Jst4fun321]

Re: 2000 Mercruiser 5.0L EFI stalls when warm/hot

UGH... I think I have the EXACT same problem. Your description matches my boats behavior perfectly. I have a 5.0 Merc. in a 1998 Cobalt.

I paid a local boat shop to go for a ride along. Luckily I drove it for 30 min before he got there, because it didn't reproduce at first. Was driving perfectly actually, the. Just cut out when I got above 2k rpm. Would restart fairly easy, and idle or go slow fine, but cut out at higher speed or heavy load.

He hooked up his laptop, and when it failed, the engine did throw a few codes related to timing. He made some calls and concluded it was one of two things, either the timing sensor or the whole ECM.

Long story short, we tried the sensor replace and I took the family out, seemed to run great, and the DEAD. Now it would die as soon as the I moved out of neutral, and then could not even start. I had to be towed back to dock.

They tell me the ECM is $1600 or more!!! I would happily spend that if I was sure to never have this problem, but my confidence is low. Waiting on call from the shop today and I need to decide.

Would greatly appreciate any feedback on where to buy the ECM or anyone else with similar problem. We should even talk on the phone and compare notes. Desperate to figure this out.

Thanks in advance. I will post what I learn.

 

[Jst4fun321]

Re: 2000 Mercruiser 5.0L EFI stalls when warm/hot

FYI - searching another thread on this forum, I found this, which proposes a jumper wire test which confirms if it is the ECM or not. I was hoping not the ECM. Again, anyone know where to buy ECM for better than I can get from repair shop?

http://forums.iboats.com/mercruiser...02-merc-engine-cuts-out-no-reason-511408.html

UGH... I think I have the EXACT same problem. Your description matches my boats behavior perfectly. I have a 5.0 Merc. in a 1998 Cobalt.

I paid a local boat shop to go for a ride along. Luckily I drove it for 30 min before he got there, because it didn't reproduce at first. Was driving perfectly actually, the. Just cut out when I got above 2k rpm. Would restart fairly easy, and idle or go slow fine, but cut out at higher speed or heavy load.

He hooked up his laptop, and when it failed, the engine did throw a few codes related to timing. He made some calls and concluded it was one of two things, either the timing sensor or the whole ECM.

Long story short, we tried the sensor replace and I took the family out, seemed to run great, and the DEAD. Now it would die as soon as the I moved out of neutral, and then could not even start. I had to be towed back to dock.

They tell me the ECM is $1600 or more!!! I would happily spend that if I was sure to never have this problem, but my confidence is low. Waiting on call from the shop today and I need to decide.

Would greatly appreciate any feedback on where to buy the ECM or anyone else with similar problem. We should even talk on the phone and compare notes. Desperate to figure this out.

Thanks in advance. I will post what I learn.

 

[alldodge]

Re: 2000 Mercruiser 5.0L EFI stalls when warm/hot

UGH... I think I have the EXACT same problem. Your description matches my boats behavior perfectly. I have a 5.0 Merc. in a 1998 Cobalt.

I paid a local boat shop to go for a ride along. Luckily I drove it for 30 min before he got there, because it didn't reproduce at first. Was driving perfectly actually, the. Just cut out when I got above 2k rpm. Would restart fairly easy, and idle or go slow fine, but cut out at higher speed or heavy load.

He hooked up his laptop, and when it failed, the engine did throw a few codes related to timing. He made some calls and concluded it was one of two things, either the timing sensor or the whole ECM.

Long story short, we tried the sensor replace and I took the family out, seemed to run great, and the DEAD. Now it would die as soon as the I moved out of neutral, and then could not even start. I had to be towed back to dock.

They tell me the ECM is $1600 or more!!! I would happily spend that if I was sure to never have this problem, but my confidence is low. Waiting on call from the shop today and I need to decide.

Would greatly appreciate any feedback on where to buy the ECM or anyone else with similar problem. We should even talk on the phone and compare notes. Desperate to figure this out.

Thanks in advance. I will post what I learn.

Jst4fun321 welcome, this thread is mostly leading down the road of the lack of fuel causing the issue. The more I think about it the more I'm leaning to vapor lock due to the OP idicated he has spark. We are waiting to hear back if the issue has resolved or needs further investigation. This being said, to obatin best results and get the most input from the forum is to post a new thread. This will be noticed by more folks and give you the best chance of fixing the problem. You don't hear much about ECM's failing but it is possiable

 

[41 Keys]

Re: 2000 Mercruiser 5.0L EFI stalls when warm/hot

I have a 2000 mercruiser 5.0 EFI installed in a 2000 Searay 120BR. Ignition is Thunderbolt V. I'm the original owner, engine is completely stock. 2 years ago I had a Vapor Lock issue which was rectified by installing the mercruiser check valve in the cooling system between the fuel cooler and thermostat housing. I have not had any other problems or issues with the motor. I had a dual battery setup installed with Off-1-Both-2 battery switch using Optima Blue Top batteries during the winter by a local marine center.

Memorial Day weekend engine ran great, no issues all weekend. Took a 45 mile ride plus pulled skiers/tubers all weekend.

Week of the 4th of July launched boat and drove approx. 2 miles to dock. Approx. 2 hours later I started the engine to take tubers out. Engine started and idled fine. All gauges were reading normal. After approx. 5 minutes RPM fluctuated between 400 - 1000 with associated engine surging for a second or two then engine died. Engine would start for a second or two and then die again. I disconnected the fuel line at the Throttle Body and turned the key to run. I got the normal 2 beeps heard the fuel pump relay click and pump ran for the required 2 seconds but no fuel came out of fuel feed line. Thought i had a bad fuel pump so i replaced it and the cooler as it comes as a kit. Fuel pressure regulator did not come with kit so it is the original. Without going into great detail, I've eliminated the fuel system as a cause.

Took boat out last weekend took approx 5 mile ride and pulled a skier. While switching skiers engine at idle I got the same stalling condition as discribed earlier. The coil felt hot, but I'm not sure how hot it should be. I pulled the coil wire off the coil and the connector was still in the coil. I installed a new coil wire and took boat out and ran it hard for about a half hour. After being back a dock for a few minutes engine started, ran for a few minutes then same stalling condition. Once engine cools it starts and runs fine for a while then same thing occurs.

I'm petty sure my issue is electrical. When engine won't start I pulled the coil wire of the coil and while cranking engine I get spark arc between coil wire and coil, but I'm not sure how intense the spark arc should be. Thinking I might have a intermittent short, I have wiggled a shook the engine wiring harness all over paying particular attention to areas of the harness near sensor connection points but I have not gotten the engine to stall or even hesitate. Once the engine gets hot, same thing all over again. I've checked all connections to ensure they a tight and no corrosion was present.

Failure doesn't occur after a specific amount of engine run time as the failure occurs after various amounts time running.

I believe heat and electrical are the primary causal factors.

Anyone have any ideas?

Sorry this is so long, but I want to get all the facts in.

I have your solution. I had same problem with 1980 mercruiser 228. All was fine until I started idling or trolling. Run your engine exhaust fan. Your engine shroud makes the engine too hot when idling. When you are motoring fresh air gets into the shroud and all is fine. I installed a 170 cfm 12 volt fan to take care of it after 2 years of grief.

 

[Jst4fun321]

Re: 2000 Mercruiser 5.0L EFI stalls when warm/hot

thank you for the note. definitely could be heat related, but I wonder if you might have had a different problem, because mine does not occur when idling. The typical scenario was just running 20-40mph cruising, and engine would cut out. So it doesn't seem like idling was the problem. but I'm willing to try anything. Not sure where I would position the fan or what specifically needs cooling.

I have your solution. I had same problem with 1980 mercruiser 228. All was fine until I started idling or trolling. Run your engine exhaust fan. Your engine shroud makes the engine too hot when idling. When you are motoring fresh air gets into the shroud and all is fine. I installed a 170 cfm 12 volt fan to take care of it after 2 years of grief.

 

[Jst4fun321]

Re: 2000 Mercruiser 5.0L EFI stalls when warm/hot

Thanks. these sound so similar that I thought it would be good to share data here first.

I don't understand vapor lock interaction. does that make sense given that it would not start, then after it cooled down it started fine?

Jst4fun321 welcome, this thread is mostly leading down the road of the lack
of fuel causing the issue. The more I think about it the more I'm leaning to vapor lock due to the OP idicated he has spark. We are waiting to hear back if the issue has resolved or needs further investigation. This being said, to obatin best results and get the most input from the forum is to post a new thread. This will be noticed by more folks and give you the best chance of fixing the problem. You don't hear much about ECM's failing but it is possiable

 

[Usspikes]

Re: 2000 Mercruiser 5.0L EFI stalls when warm/hot

I'm the original poster of the thread.

I had a vapor lock problem about 2 years ago and fixed it by istalling the Mercruiser Check Valve in the raw water line between the Fuel Cooler and the Thermostat Housing MC PN 21-862271A1 you can also Google the Service Bulliten 99-7. It will explain what vapor lock is all about. I had absolutely no problem with vapor locking all last summer and this past Memorial Day weekend.
The problem I'm have now as described at the beginning of this thread did not show up until the week of the 4th of July.
In a nutshell vapor lock occurs within 30 - 45 minutes after shutdowm which is essentially the Heat Soak time.

 

[alldodge]

Re: 2000 Mercruiser 5.0L EFI stalls when warm/hot

I'm the original poster of the thread.

I had a vapor lock problem about 2 years ago and fixed it by istalling the Mercruiser Check Valve in the raw water line between the Fuel Cooler and the Thermostat Housing MC PN 21-862271A1 you can also Google the Service Bulliten 99-7. It will explain what vapor lock is all about. I had absolutely no problem with vapor locking all last summer and this past Memorial Day weekend.
The problem I'm have now as described at the beginning of this thread did not show up until the week of the 4th of July.
In a nutshell vapor lock occurs within 30 - 45 minutes after shutdowm which is essentially the Heat Soak time.

For the most part my boat started doing about the same thing. I have the VST system which makes it worste with the tank sitting on top of the engine. I also added to the problem by starting off the year with gas bought cheaper from the local station during the winter. After I managed to get most of it burned off and started using marina gas. Most of the marina's at our lake have no ethonal added, and I also removed the heat and sound material between the deck and the engine, and I make sure to idle a bit more. So far it has stopped but it also has not been as hot as last summer. If it starts doing it again I'm going to move my VST return lne to the gas fill neck which others have tried and no complaints have been heard.

 

[boater_2018]

Long shot here, but I’m having the exact same issue and have not been able to find the problem yet. Was is ever resolved?