150 mariner mis fire

[nfrock40]

I have an older model mariner

I have an older model mariner 150. Not sure of the year i cant find a serial number. I just rebuilt the carbs and got it running. It starts and idles great. At mid-way acceleration and running it seems to be mis firing. But once i open it all the way up its great. Any body know how to check wich cylinder is mis firing

 

[fastjeff]

"'Bout the only way is to

"'Bout the only way is to make it do this for several minutes, then shut it right down and pull the plugs. (Don't allow it to run more than a few seconds when you chop the throttle.) The misfiring plug will be darker.

Might be a bad coil or wire or the plug itself.

Jeff"