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1978 Merc 110 9.8hp

R

robshaver

New member
Not sure if anyone else has had this problem, but this nice little motor runs great except at the lowest of idle. One cyclinder stops firing and the motor will quit 50% of the time. Turn the idle up on the tiller just a hair and both cylinders keep firing. I've changed plugs, made sure they are staying clean and dry, but the situation still persists. It's not as bad if I use the motor each day, but leave it for a few days between uses and the problem returns.

Am I looking at a coil issue or a carb issue? Any suggestions on what to try would be greatly appreciated.

Thanks,
Rob
 
Put the ignition to a real test and see if both cylinders will fire across a gap of 3/8" or better.------The carburetor feeds both cylinders.-------There may also be an issue with the bottom crankcase seal leaking.---------Lots of work to replace that one.--------
 
You can use a timing light to determiine if in fact you are loosing spark and to which cylinder.-----------If that is the case then swap the coils and see if the problem follows the coil.------Always test and trouble shoot before spending $$$$$$$$-------Might not hurt to do an ohm check on the stator and trigger coils.
 
Very good idea to switch the coils. I didn't think of that. Thanks! I have a timing light so I will try your idea. Not sure, barring the result of that, if I know how to do an ohm check on the stator and trigger coils. I'll leave that for another day!

Thanks again,
Rob
 
If you do, but sure to label and diagragm where the wires came from! Or else!

I suspect a bad coil. Seen a lot of them lately--two on one motor.

Jeff
 
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