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70 hp merc missfire

kevin

Member
well
its got me i still bele


well
its got me i still beleive its the switchbox because i have changed the wires from the trigger over and it moves the spark
They way i have worked it out is the genertaor coil under the flywheel generates the charge which is stored in the switch box capacitiers the pulse from the trigger then releases this charge to the main ignition coils so by moving the trigger output wires to the switch box confirms to me the trigger is ok along with the coils so the switch box must be u/s
yours thoughts would be great
 
"Kevin.... The Mercury engine

"Kevin.... The Mercury engine is not my line of expertise but in looking at your explanation as if it pertained to a Evinrude or Johnson, my thoughts would be as follows. Also, to keep it simple, I'll scale this problem down as if it pertained to a two cylinder engine.

The engine had spark on the top cylinder and none on the bottom cylinder. You reversed the wires leading from the sensors (triggers) to the powerpack (switchbox).

The spark now reversed itself so that the bottom cylinder had spark, but none on the top cylinder.

This proves that the circuitry within the powerpack is okay as the pack is now firing the opposite cylinder. This would indicate to me that the sensor (trigger) that normally fires the dead cylinder is faulty.

I'm sure that Tony will jump in here in short order to give his professional explanation as he is more qualified than I in the Mercury line.

Joe
"
 
" Kevin,

Joe's line of


" Kevin,

Joe's line of reasoning is clear and accurate, as usual. I would suspect the trigger coil also.

Tony "
 
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