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First recorded activity by BoatBanter: Jul 2006
Posts: 5,275
Default Mercury 3 cyl 90 HP one cylinder with no spark

"Holten" wrote in news:1157904642.227574.96390
@h48g2000cwc.googlegroups.com:

Hello

I have one of these motors.

One of the cylinders dont have a spark.
One man told me it could be the trigger.
How can I find out if he is right ?
Can a trigger be repaired ore do I need to buy a new.

Regards from Denamrk

Holten



Doesn't this have 3 spark coils on it? I had the V-6 175 Merc and every
cylinder had its own spark coil. I'd be tempted to swap it first before
I tore into the stator windings where the trigger coil is located.

My Mercury trashed its original stator coils because some idiot left the
soft iron core of the stator exposed and the salt air ate it. The
resulting rust shorted the core's magnetic field with an eddy current
path so spark was very weak and finally made it skip like mad. My boat
mechanic replaced the Mercury stator with an aftermarket product and
coated the exposed core surface with a thin layer of axle grease to keep
the wet air from rusting out the core. After that, if you knew what was
good for you, you didn't put your hand anywhere near a spark plug wire or
coil as you found out why they called it "Thunderbolt" ignition. Spark
it produced was most impressive, indeed.

If all the spark was poor, I'd go for the stator problem first....but
with one plug dead and the rest with good spark, I'm pointing to the
separate coils Merc uses, which are easy to get to on each cylinder head.
Only one winding has to have a shorted turn or open tiny fine wire to
stop the spark.

The trigger coils are under under (or was it over) the stator coils under
the flywheel. Stator magnets are all the way around, closely spaced.
There was only one trigger magnet passing the trigger coils as it went
around....smaller coils, too.



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