OK so the computer came back from Crockett unlocked and the plug wires came in but I’m still stuck. Installed all new wires and did some test rides only to find I am back to where I started. The scan tool picked up 1 code (34) MAP Sensor low voltage. I cleared the code since I don’t know if its new or old and was not able to get it to come back after a good 1/2 hour of testing and having the power issue the whole time.

Its runs lousy then clicks on with normal power for like 30 seconds then cuts off for a minuet or two and back threw they cycle over and over again. Feels like it gets a surge for power the its up. All grounds are clean, connections have been checked and fuel is clean as a whistle. Its also holding pressure at 42lbs on off the fuel rail, right where it should be. I have 3 batteries and tried it on either side with no difference as well.

I have a MAP sensor going in tomorrow but as I can not reproduce the code I’m not feeling like that’s going to get me anywhere. I am thinking the next thing to try here might be the crank position sensor as I hear they are common and can not pop up codes.

Anyone know the GM part number?

Also I am open for ideas again…….

I did have that problem in my 8.1 02 GMC 2500 hd.

What was the issue ? Crank sensor ?

Yes crank sensor. It would die an restart. or run funny at times. Never had a code. The sensor is in the back of the block an reads the crank from behind the flywheel. I'm not saying this is Your problem, Just what My truck did. Good luck. Artie

Behind the flywheel? Jay, I am not sure i can help you with this one.....hahaha

4bus , your the skinniest guy I know, who else can do it..

Looks like its right below the head on the port side, hopefully accessible.

Thats it. It was really hard to change on My truck. Good luck an let us know what You find as far as the fix. It shouldn't be to bad on a boat. Artie

That's not bad, top side mount will be easy, that must have been a pain on the truck!

Why don't you pick the boat up from the hack of a mechanic you sent it to and I will backprobe the labscope directly to the sensor and see if we have an intermittent on the crank sensor? Good chance the computer is not seeing it because of the low diagnostic sample rate of the MEFI4

Let Me know what your readings are please. I think Your on the right track. Yes on My truck it was hard to reach with all the truck in the way. LOL. Be carefull not to break it off. I used kroll on it an let it set. It worked. Artie

Did You get it replaced or boat repaired ???