Evinrude misfire

[Trawler Scott]

I have a 1997 50 h.p. evinrude ,it starts imediately , idles without stalling and the top end power is smooth but...at idle and up to the middle rpm range it sounds like it has a misfiring cylinder . I decarbonized ,adjusted the idle mixture and put in new plugs (it didnt help) The new plugs may have helped until after running at speed the the roughness returned .When I pulled the plugs today the #1 and #3 plugs were a slight black coating all over (dry - damp ,not wet) the #2 plug was wet on 1 side (oily) with I am guessing was a slight carbon buildup .<br />Any ideas ? <br />Thanks

 

[fireman57]

Re: Evinrude misfire

Sounds like you may need to clean the carb. Might have some crud in a jet. If you engine does have a dead miss you can tell. When it does this leave the throttle were it is and have someone with insulated pliers pull and replace the plug wires one at a time. If your rpms do not change then you are losing fire to that cylinder. Try pumping your primer bulb when it does this too and let us know what happens. If we can't figure it out then you will just have to send it to me because you won't want it. I'll even pay shipping.(humor)

 

[Trawler Scott]

Re: Evinrude misfire

Ha ! I think I will hang on to it ... I ran it today and each plug wire seamed to affect it the same . I didnt notice any difference when squeezing the bulb , I could do it repeatedly and maybe notice a slight stumble. Any ideas ?

 

[fireman57]

Re: Evinrude misfire

If you just did a decarb you will want fresh champions in it as it trashes the plugs. Try this first and post back the results. Contrary to most thinking you really can't clean up a plug. If you do a lot of idling or slow trolling try gapping them ten thousandths over.