Idling higher when warm

[TheFormerlives]

I've got a 1988 Evinrude 100hp engine that cold starts fine and idles at around 800rpms. But after running at WOT for about 3 minutes, or once it gets warm I'll drop it back to neutral to idle and it'll idle around 1300rpms. Needless to say I don't want to do damage by shifting while the RPMS are that high.

What could cause this guys? I'm stumped. Thanks.

 

[Daviet]

Re: Idling higher when warm

Is you throttle cable adjusted properly?

 

[TheFormerlives]

Re: Idling higher when warm

Yup throttle cable is properly adjusted. Like I mentioned, during a cold start it will idle fine. But once warm it will idle higher.

I really don't know what to think.

 

[jtexas]

Re: Idling higher when warm

potential lean burn (more air, less fuel). that's trouble because less fuel means less oil.

is dirty oil accumulating on the engine?

 

[TheFormerlives]

Re: Idling higher when warm

To be honest I just bought this engine from a Marina a few days ago. I can't tell for sure if oil is accumulating. Whats the best way to determine that, check the plugs?

Are there any other symptoms that would make an engine idle higher when warm?

 

[TheFormerlives]

Re: Idling higher when warm

Anybody have some insight?

 

[jtexas]

Re: Idling higher when warm

To be honest I just bought this engine from a Marina a few days ago. I can't tell for sure if oil is accumulating. Whats the best way to determine that, check the plugs?
...

nah, not the plugs, I mean on the engine itself, under the cowl. Don't worry about that now though, shouldn't have brought it up.

spray some carb cleaner or gas around the intake manifold, if RPMs react, it's sucking air.

Talk to the marina about it...go in & chat with the mechanic if you can, bypass the sales guy, if they get defensive you might not get as much cooperation. Find out about the maintenance history, when was the last carb rebuild, water pump, etc. and anything major.