96 Challenger Randomly Dies

[derek.mcbill]

I have a problem that has been going for about a month. 96 challenger (787 engine) will die randomly. Often happens on acceleration, but also happens at cruising speed. No beeps at all, and all I have to do is shift into neutral and press the button, and instantly it fires up. I have changed fuel, new fuel filter, new plugs, serviced rave valves, and loaded in a bunch of carb cleaner. Almost all of these things seem to help - a bit... enough to leave me scratching my head. I also am questioning the charging system in the boat - battery (new) is not that strong (also recently charged). Suspect it may be MPEM or some other black box. I am looking for advice before I unload several hundred dollars chasing an electrical bug.

 

[CaptSteve]

Your problem may be a bad DESS post. I would check the wiring on the DESS post and make sure it is tight and clean. I would also clean the contacts on the lanyard and the post with a pencil eraser. Randomly dieing is more often a DESS problem.

 

[Flightfollowing]

did you figure out what was wrong?

 

[Phildoo]

Wouldnt be the MPEM. Is it stalling? or stuttering?..or just shuts down?

 

[derek.mcbill]

Well it seems that the problem may be solved. I had a starter die just before these problems started to happen. It was such a &%$ to work on it that I took it to the marina and let the poor guy there replace it. Well the rebuilt starter died a few weeks later and the shop replaced it no charge. When I put the boat back in the water in ran like crap. I looked at the engine and found than when the guy working on it had sprawled all over the engine, he had pulled the wire out of the spark plug cap. So I fixed that and the problem has completely gone away. So my guess is that the first time they swapped the starter, they compromised the lead to one plug and depending on the strength of spark needed for ignition and/or the vibration in the engine, it would not fire. Would that cause it to instantly die? Don't know how the starter could affect this issue, so my guess has to be the integrity of the ignition wires.

 

[Gamerse]

What plugs are you running btw?

:cheers:
Ernest