Spark Test Question

[Doug Market]

I have a '92 120 Johnson that has no power. I re-built the carbs but the problem still exists so I preformed a spark test and found that 3 of the 4 leads will show spark at a .02 gap and one lead I had to adjust the tester slightly under .02 to show spark. The QL78YC plugs are gapped at .03 so I have to conclude that either my coils, power pack, or stator is dying.? I replaced my power pack last year due to NO spark so the PP is only a year old. Is it safe to assume the coils are the issue? I am willing to bet that they have never been changed on this motor, I just find it odd that they all would weaken simultaneously.

Any guidance would be greatly appreciated.

Thank you.

 

[jonesg]

Re: Spark Test Question

You basically have no spark at all, the gap should be set to 7/16th inch, thats almost half an inch. And it should jump with a bright blue spark, yellow is failure under compression. A spark test cannot be done with a spark plug.

Anyway, remove a coil and inspect it closely, turn it over in your hands and look very closely for little cracks, especially in the potting epoxy.
Maybe you'll find they're all cracking. Also look for corrosion where the coils mount, thats the ground contact and it must be clean.
Check plug wires too.