Arching At Ignition Coil

[Mzzola]

I have a 1998 MerCruiser 4.3LH Alpha Engine. I have a loud popping noise that almost sounds like backfiring, that I have found to be an electrical arch jumping from the center wire on the ignition coil to the positive or negative terminal (not sure) also on the top of the ignition coil. I have replaced the ignition coil two seasons now in a row. In the past, I replaced the center cable from the distributor cap to the ignition coil with a heavier gauge wire and this stopped the problem until now. The voltage gauge on the boat is not very accurate. A had held voltage meter checked at the terminals of the voltage meter, while the motor is running, reads almost 14 volts. Is this a normal voltage reading? Any ideas about what is causing this arching and the ignition coil to burn out? Thanks from Mike

 

[Don S]

Re: Arching At Ignition Coil

You have a crack in the coil tower. Replace the coil.
You may also have a bad plug or plug wire that will not allow the coil to fire and is causing the crack. When was the last time your engine had a full tuneup and maybe new plug wires?
14.0 to 14.5 while running is a normal reading and is not causing your problem.

 

[Mzzola]

Re: Arching At Ignition Coil

d

Thanks Don!

I replaced the plugs and plug wires and the coils twice now. Maybe they weren't done in the right order? I'm going to do it again this and post the results.

Thanks again,
Mike

 

[Don S]

Re: Arching At Ignition Coil

Have you done them all at the same time?

 

[Mzzola]

Re: Arching At Ignition Coil

Have you done them all at the same time?

No, I just checked and they were done at different times. I'm going to replace them all this week and hope this solves the problem.

Thanks again for your advice!
Mike
Mike