Jumpy RPM on 28hp Evinrude

[jeepers]

Hey all,

i posted about this a couple of weeks ago and got some good responses regarding speed expectations (thanks again guys!) but still need some help with the unstable RPM's.

The RPM's just jump for a few seconds and then drop back down. i've gone through and re-adjusted the needles and the throttle sync but these haven't had any effect. i've got the flywheel off at the moment and am going to be double-checking the gap and timing this afternoon. Fuels _seems_ to flow well but it's pretty tough to tell.

i've put an editted version of the video i took here for review.

http://www.youtube.com/watch?v=xABoRVJ8QcU

thanks in advance,
dean

 

[Mr. Bwok]

Re: Jumpy RPM on 28hp Evinrude

Did you ever find out what the issue was? I would love an update. I am having a similar problem.

 

[jeepers]

Re: Jumpy RPM on 28hp Evinrude

Hey Mr. Bwok,

i haven't been able to get back out on the lake for testing to be positive but changing up the coils seems to have resolved my issue. i've had it out for a few runs and it works well but i haven't recreated the scene where i had it just running in the boat launch. My thought is that it may also have been due to cavitation.

When changing the coils i found a wire that was rubbing on the shaft and had no insulation left but that shouldn't really affect anything as it was supposed to be grounded anyway.

hope that helps. if i get a chance this weekend i'll try to do a bit of elimination testing and i'll post back my results.

 

[tashasdaddy]

Re: Jumpy RPM on 28hp Evinrude

take an induction timing light with you. just clip it on to the plug wire. it will show you if the spark is breaking up.