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Johnson 18hp runs on single cylinder

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mikechase

New member
" Hello -
I have recently acq

" Hello -
I have recently acquired a '63 18 hp Johnson. It runs only on the lower cylinder. Both cylinders have similar compression, spark at both cylinders. Disconnecting the upper plug wire while running makes no noticeable difference, disconnecting the lower stops the engine. I've swapped plugs with no change. The upper cylinder is getting fuel - the plug is wet when removed. Any suggestions on what to check next?

Thanks!
Mike "
 
Pull the flywheel and remove

Pull the flywheel and remove the coils and have them tested on a mercatronic tester. Coils are a problem on the older OMC motors
 
Thanks Sparky - both coils we

Thanks Sparky - both coils were cracked - replaced both and now it runs great.

Thanks again!
 
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