Mercury 90hp Inline 6 1985 Tower of Power weak spark

frankrizzo

Cadet
Joined
May 5, 2014
Messages
21
Fixed several problems now it runs great but still needs work.
I removed carbs and cleaned them, bowls were extremely dirty, changed floats and needle and seat on one that was leaking.
Was missing spark on several cylinders but after cleaning all of the terminals on coils and switch boxes i now have spark in all cylinders and it runs well however when i put the test light on each plug 1 3 and 5 were extremely bright and 2 4 and 6 are a lot dimmer.

Not sure what i should work on first to trouble shoot this.
What are the logical steps?
I was thinking tomorrow i would move the switch-boxes around and see if the dim spark follows.
If it does, I would assume i have a bad switch-box my local marine repair shop stated they have the switch boxes in stock but they said if the part number ends in A1 you have to do both at the same time. Is this true? Mine are A1's.

Other possibility if the problem does not follow i need to change out the trigger?
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,616
Swap the red/blue stator wires between switchboxes, if problem follows the stator is weak on that bank,,,,
 
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