on and off

[bryan miller 1969]

Hey guys ! I bought a 1989 Evinrude 20 hp a couple weeks ago in very good shape .Starts in 2 pulls and idles great.Also runs great for about 3 miles too my fishing spot .I start it too come back and it runs great until I get planed out and at full throttle then it is like turning a switch on and off almost like I am unplugging the kill switch then pluging it back in very fast.on off on off on off.Half throttle is fine.Seems like the coils are going off and on off and on.Hope I explained that correctly .HELP PLEASE .Thanks

 

[Boobie]

Sounds like an ignition problem. Put a timing light on it when it does it and look in to it for black spots.This will be the cylinder with the ignition miss.