Coil burning out
 

While fishing this past week everything was running smooth when with no apparent reason engine quit running. Coil was extremely hot! After being towed in replaced coil went back out 45 minutes later same thing again! Now new coil no spark electronic module appears to be no good! What could be causing this mechanic wants to rebuild engine. Never had a coil issue the 4 years I have owned the boat! Engine is a 260hp 350 mercruiser 1984

Id try another coil,,and maybe just do a tune up,cap,rotor plugs,wires.

Does you 1984 ignition have points by any chance ?

BTW: how do you know your coil was bad ? And not the module going out. And what makes you now think the module is bad now but not before ? Basically, asking for what your diagnostics where.

Wait, did I just notice re-reading your mechanic wants to rebuild your engine over a coil issue or did you fail to mention other things ?

there may be no dwell left in the module or its outputting to much voltage.

Coil
 

Mallory electronic ignition replaced coil went fishing again. 45 minutes later no spark again. Took it to a marine mechanic who told me module burned out. He replaced electronic ignition and coil ran 5 minutes back to no spark again. Told me no charge pick it up he don't know what is wrong with it and get it out of his yard. True story!

whats the alternator putting out for voltage?

Coil
 

13

Is it possible you got the wrong replacement coil or you left the key on before running it ?

Coil
 

yes it is possible. I have ordered a replacement distributor with ignition and coil! I will receive it all in a couple days.. I will let you know how things turn out the end of this week!

Triple check you have no bare 12v leads for the ignition. Should be purple wires IIRC in the merc harness. I pinched one once and was chewing thru coils till I found the short.

great point,,my friend had that same problem.2 gm new style coils burned up.that was a head scratcher.

I will definitely be checking the harness for a short it sure sounds like a short to me. Thank you for your help. I will let you know what I find

Merc harnesses have more than one switched 12v wire. Spend some time with a ohm meter and test light. I bet you can find your problem.

I found a plug wire that was pinched in the steering back side of the motor. Could that cause a direct short or just a misfire? It had worn through the insulation on the wire!

the coil is trying to fire that plug through the cap and possibly being sent to ground so I can see this being an issue, and yes misfire fo sho

Thank you I've got new distributor coil wires and plugs just scared to death to turn the key and burn something up again! I'll mix up a stiff drink and turn the key!

make sure you get the firing order correct, you dont need to chasing another problem

One at a time

Thank you everyone for the help! The ignition switch was bad. We are back and running ! Thanks again