power loss issue

[pyrotech]

I have a 1975 85hp evinrude it starts and runs fine until the boat barely starts to plane then it dosn't kick in to finish out the plane. any thought or ideas would be helpfull

 

[emdsapmgr]

Re: power loss issue

Once the engine warms up fully, check each spark plug wire for spark. That engine will seem to run fine on 2 or 3 cyls, but you need all 4 to plane it out. A timing light will show you the quality of spark on each plugwire. It may run fine when cold, but check it when it's fully warmed up..

 

[boobie]

Re: power loss issue

Pull each spark plug wire off when the the prob occurs and look for a cyl with no power drop in rpm. That's the bad one. aka; cyl drop test.