Evinrude rough at top end.....update...

[acc]

Bought this '93, 40hp, Evinrude boat from a guys barn...I've put maybe two hours running time on it....<br /><br />Seems to run great for a while and maintains full power all the way to redline....If I press the choke button it slows the engine as expected. <br /><br />Then, it becomes rough at the top end as if a gremlin has entered...Intermittently pushing the choke button smoothes it out so it must be running lean....<br /><br />Idle is good/Midspeed is OK/Fishing is great...<br /><br />thanks fot any suggestions<br /><br />curtis

 

[steelespike]

Re: Evinrude rough at top end.....update...

I suspect a fuel supply problem,Is the primer bulb firm ?Try squeezing it, if it helps then it could be the fuel pump.If bulb colapses it could be a blockage between tank and bulb or a poor vent.

 

[acc]

Re: Evinrude rough at top end.....update...

Thanks Steel...<br /><br />Tried bulb squeeze first.....didn't work....<br /><br />I too believe it is a fuel supply problem....My manual comes in on Fri or Sat....Then I'll start looking at serious stuff......<br /><br />In the meantime, fuel filter is next.... maybe drop the carb bowl and see what that looks like...<br /><br />thanks<br /><br />curtis

 

[acc]

Re: Evinrude rough at top end.....update...

Bump....seeking more advice....

 

[acc]

Re: Evinrude rough at top end.....update...

Update.....<br /><br />I replaced plugs with Champs....It had Autolite but they didn't look bad and gap was OK.....<br /><br />I tuned the low speed adjustment......<br /><br />That's all<br /><br />Today it ran great at idle, mid, high and WOT...<br /><br />So, for now, this problem goes away but I don't think any of those things(above) fixed it....<br /><br />thanks<br /><br />curtis

 

[DJ]

Re: Evinrude rough at top end.....update...

acc,<br /><br />I think the "Champions" fixed it. I've never run anythung else in an OMC and I've never had any trouble.