Evinrude surges at high trottle

[Dave Smith]

I have a 1996 Evinrude 115 OB. This engine has 150 hrs. Engine surges at top throttle with the rpm surging up and down appx 400 rpm with boat speed doing the same. This motor has done this since new. Dealer has tested three times and says motor is puting out rated hp and refuses further help. Motor starts and runs normal other than the high speed surging. I'm desperate! Help!!

 

[clanton]

Re: Evinrude surges at high trottle

60 degree looper right? Check for arcing between ignition coil and plate between coil and power pack, Connect vacumn guage with a T into fuel line as close to fuel pump as you can get,full throttle in water loaded number should be 4 inches or under. Check power pack output to coil, full throttle in water loaded with peak reading meter. You have to watch the meters when it surges. If this is warranty work, call the bomb and complain, if not look for a different mechanic. what is compression, what do plugs look like, what is rpms when the engine surges.

 

[clanton]

Re: Evinrude surges at high trottle

Engine could be 90 degree crossflow, need to know this.

 

[jegervais]

Re: Evinrude surges at high trottle

If its the 60 degree looper, don't overlook the optical ignition sensor... Tell us the model number so we can determine exactly what you have. <br /><br />-John

 

[clanton]

Re: Evinrude surges at high trottle

bump