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Rod McInnis
 
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Default 5.7L Merc coil question


"Coff" wrote in message
om...


It was arcing to BOTH the positive and negative
terminals on the top of the coil. Needless to say, with 120 gallons
of gas about 3 feet away, I shut the engine down immediately.



Was the rubber boot on properly?

Was there any water or anything similar splashed across the coil?

Were all the spark plug wires properly connected?

The spark should follow the path of least resistance. Normally this
requires it to jump a very small distance, the "gap" of the sparkplug. If
it jumps some place else, then it is because either the someplace else was
an easier path or the sparkplug path was not available.

Adding a film of water, dust, etc. across the coil could make that an easier
path. If that is not the case, then I would trace down the sparkplug wire
path, including the distributor cap. The fact that the engine was able to
run indicates that at least most of the cylinders were getting spark, but I
would suspect that at least one was not. You should be able to isolate
which cylinder by removing spark plug wires one at a time. If you remove
one and the engine slows down, that plug was working. If you remove the
wire and there is no change in the engine, that plug was not working.

The problem could be the plug is fouled or broke, the wire is broke, or
there is a problem in the distributor cap (it is not uncommon for the cap to
crack or actually have one terminal break off internally).

Rod