2005 5.0 MPI shutting down and restarting

OllieC

Chief Petty Officer
Joined
Dec 8, 2011
Messages
533
S/N 0W037286

I posted on another thread about a month ago which is a no-no, however I was hoping to have the solution solved and yet no joy.
My engine, once it starts to warm up, is stalling or shutting down, then the restart beep comes on and the fuel pump. I’ve had two different service techs look at it. One was a general service tech without a scan tool and the 2nd is a Mercruiser mechanic with a scan tool.

After the 2nd tech looked at it and scanned it, he picked up no trouble codes. However, when the engine was stalling or shutting down, it was also erasing is information on the laptop, from what I was told. The only thing they could deduce was that it was the ECM. So I bit the bullet and ordered a new ECM. They installed it and said it ran without issue in the tank and that I should try it out on the River.

Because of circumstances beyond control I had to wait about a week and a half, so I brought it up to the lake instead. Well, after it warmed up, the issue reappeared. Of course I am not happy because I just wasted IMO $2k on a non- returnable ecm.

I did work on the engine and had the same outfit rebuild the outdrive last Fall. Here is a list of the engine maintenance I did over the Spring.
1. replaced manifolds, risers and elbows - dry joint and Mercruiser
2. NGK spark plugs, gapped, new cables, rotor and cap.
3. New Starter
4. New IAC and muffler ( thinking that was what was killing the engine)
5. New serpentine belt
6. Rebuilt Hardin Marine Gen 7 sea pump
7. New thermostat 160 degree
8. New ignition switch (snapped the key in it so replaced)
9. I have a cool fuel 2 system - every year I replace the twist on filter, use non-ethanol gas, treat it as well, and keep the tank full.

As it warms up, it runs smooth and quiet.

So I’ve read that another possible issue is the Crank Position Sensor. On my year of motor, if you have a defective one, it will not throw any codes or put the motor into guardian mode. I’ve read that the engine stalls and the computer gets confused. I just went to Napa and purchased one and haven’t installed it yet. I need to take a break for a few.

Any other ideas? I have spark, air and fuel. This is clearly electrical IMO. Could the coil be going bad? If the coil goes bad, would it stall the motor as it warms up? I would think it just wouldn’t start.

I’m completely out of ideas. I will, in a bit, install the new Crank Position Sensor to see if that does the trick, but at this point I’m not overly confident
 

OllieC

Chief Petty Officer
Joined
Dec 8, 2011
Messages
533
Update : I have been running at multiple rpms for 45 minutes and no stalling. I have yet to put a load on it.
 

OllieC

Chief Petty Officer
Joined
Dec 8, 2011
Messages
533
In closure, so if people search engine like I have for the past month and couldn’t find “closure” for the same issue, it turned out to be the Crankshaft Position Sensor. It was available at Napa for $75. Try that before dumping $2k on a new ECM.
 

Stinnett21

Chief Petty Officer
Joined
Jun 24, 2012
Messages
460
Thanks for being so detailed and posting back the cure. I have the 2002 version of your motor so I will keep this in mind.
 
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