1997 Yamaha 50 hp/ 4 stroke.

[horsefly60]

1997 Yamaha 50 hp/4 stroke. It used to idle at about 1800 rpm on start up. And as it warmed up it would ilde down to 1000/1200. Now when I start it .the idle speed keeps coming up. It does not want to idle down after warm up. In fact if you let it set in neutral it will keep coming up till it hits 2500/3000. Till I kill the engine. What can cause a high idle issue like this.

 

[horsefly60]

does this engine have a warm up sensor?? if so could this be my trouble?

 

[99yam40]

I have no idea, but if I was in your shoes I would be looking threw the service manual