Need help with ignition 12V intermittent cutout
 

I've been chasing this problem for two year.

randomly, always at idle, trolling, one engine ignition kills for 1 second, stalls the engine, i pull into neutral, and it starts right up. 3 minutes later, does it again. and so on

chased it to the point I have a jumper wire from ignition switch output to 12V lead on coil. now no problem

where are there connections/terminations between key switch and coil.
I know fuse box, and I guess the big plug

any advice. i have an 88 formula with twin 330hp bravos

Ram

If it's electronic ignition you may have a module going bad. When run normally it bulds heat in the output transistor and stalls. transistors cool quickly so it restarts, but then heats up again. By jumpering you may be taking the ballast resistor out of the mix and it doesn't heat up so bad. Try swapping modules(I love twins) and see if it moves to the other engine.

Thanks Inspect , but I did switch modules, but the problem stayed on the starboard side. :(

i am "guessing" that there is a loose connection on the 12V power lead path to the coil ( ends up purple wire) or hopefully not, but possibly a rubbed wire that is shorting.

on the engine..... after the big connector, then what is the path to end at the coil. what about that merc reset button and stuff (do I need that LOL)

I could get out my wiring diagram, but hope someone would tell me physical locations for these connections

once I know these I will back the jumper to each one as I go down the path, until the problem comes back, then I'll know the last leg is the problem.
that's my plan until someone enlightens me otherwise.

OH, I had this one once. It turned out to be an intermittant fuse of all things. Fuse checked good with Ohm meter, but at idle when the alternator wasnt putting out much juice and the voltage was a little lower, the higher current draw through the fuse caused it to heat up just enough to go open like a bi-metal thermostat, then it would cool and close again. Wierd, Put a new one in and try it again. Hope it works. Any of the connections could be doing the same thing

This happened to me. I finally found my problem by twisting and bending the Merc wiring harness on the engine. It finally got it to miss fire. A splice connection for muliple grounds was broken inside the harness.

If you jumped out the + voltage and it's OK, the problem isn't on the ground side. There may be a relay at the engine for a neutral interlock, or the gang plug at the engine. I would take each connection apart and clean, retighten. I need to look at my ignition ( haven't seen it in a few months....) but I do believe there is a circuit breaker with reset button.

You have the right idea with moving the jumper sequentially from point to point. Just trace back from the coil+ to the next connection, and so on...

Good Luck!
Bulldog

I would be honing in on the ignition switch and lanyard switch if so equipt. Check for loose connections or connections that are warm which would indicate high resistance. If nothing noted, do like Insptech said, swap switches with the other engines switches. Don't forget about the nuetral safety switch in the shifter either. Either one of these three switches sound like the culprit to me.

Good luck,

BT :cool:

neutral safety switch?
Is that be for the start circuit? not the ignition (ie ON) circuit?

I don' t have a lanayrd and
the jumper is AFTER the key switch. so that's out too I guess.....
i will try after the ignition fuse in the fuse panel by the helm. if no problem, then start looking at engine connectors.

My bad. I was thinking alpha with the shift interupter switch. The connection on the ignition switch could still be corroded and building resistance as it gets warm. The jumper wire would not necessarily eliminate that as a problem. Definately sounds to me like a loose wire/corrosion issue which can be detected by the presence of heat.

Good luck,

BT :cool: