1986 Evinrude 15hp engine throttle question.

[Jmstrick]

My outboard runs well except when I open it up all the way. When running at top speed it will throttle down and then back up on its own. Not sure if it's starved for gas or what. When I run at about 75% throttle or less it runs smooth and constant.

Any ideas on what can cause this and how to fix it?

Help is much appreciated!

[kbait]

Have you pumped the primer bulb while it's doing that? Compression, plugs and spark good? If yes, have a premix spray bottle ready and run it w/cowling off and air silencer removed. Go fast until it stumbles and spray a bit into the carb throat. If it picks up RPM, fuel delivery issue. If it just gets worse, could be ignition, but could be fuel flooding issue. Good luck!

[OptsyEagle]

Have you looked at the spark plugs? Could be the beginning of a plug foul. Sounds like you are intermittantly dropping a cylinder. If it keeps running well at lower power it is usually an intermittant firing of one cylinder. If it wants to stall out at the lower powers it may be a fuel delivery issue.

[MWG2600]

sounds like a air leak in the fuel line, letting air into the fuel line. Or could be the fuel pump, Mine has done that before was leaking gas line ! watch out.