'88 Yamaha 150 missing on 1 cyl

[jones64]

I have a yamaha 150 prov 1988 that is missing on 1 cylinder. i changed the coil for the plug in question, no change. the plug has a little unburned fuel on it. the cylinder cuts in and out fairly rapidly. very noticeable above 3000 rpm. seems to idle and starts well. the boat is new to me. i'd appreciate any help on this. tx.

 

[JUSTCRUISING]

Re: '88 Yamaha 150 missing on 1 cyl

whats funny is I just posted the same problem. Took the boat out yesterday with a new 19pitch prop and my boat jumped out of the water. 5 minutes later I was experiencing a misfire in one cylinder. Im not sure which number it is but if you stand at the rear of the boat facing forward it is the top right side cylinder. Keep in mind I had just changed all the plugs. In any event shut her down checked all the plugs and noticed 1 was a bit wet where as the others were dry on the tip. Ran the boat again with that plug out and it ran fine allbeit on 5 cyl's. So Im stumped...fuel / carb?

Here is my email keep me posted if you discover anything as I will do the same. I have an o/b mechanic friend who may look at it today so If I discover anything you will be the first to know...


Thanks
corenergy@telus.net