Yamaha F225 fast idle problem

[Morebills]

I have a pair of 2003Yamaha 225 4-strokes, around 400hrs,always maintained. One of them recently started giving me a fast idle when in neutral. It does not do it all the time. Very weird though because it tends to do it after a day of boating when I get back to the dock. Idle will jump to between 7-900RPM. Any thoughts? Your response is very much appreciated.

 

[rodbolt]

Re: Yamaha F225 fast idle problem

has the updates for the throttle bushings and the trhottle link rods been done?
other than that its usually a sticking ISC valve or TPS.

 

[Morebills]

Re: Yamaha F225 fast idle problem

Thanks Rodbolt,

there were two recalls on the throttle links done in 2004 and 05. I assume that is the update you asked of.

Are the two other items mentioned replaceable by me?

Thanks again for the response.

 

[rodbolt]

Re: Yamaha F225 fast idle problem

first make SURE all throttle shutters are returning to the idle position, you may have to use a techmate vacumate or similar manometer to verify this.
then monnitor TPS voltage,should see about .72V at idle.
you can remove and clean the ISC valve but replacement may be nessasary.
something is either leaking air OR telling the ECU to increase the idle speed.
you may also wish to monitor the engine temp sensor.
a faulty reading can lead to increased idle but it will be running rich and you will smell it.

 

[Morebills]

Re: Yamaha F225 fast idle problem

Can a bad thermostat cause this?

 

[rodbolt]

Re: Yamaha F225 fast idle problem

sorry for the delay, had to spend last week at kennesaw GA recertifying my master technician certs.
could a stuck open Tsts cause a fast idle? yep.
the engine could think its cold and the fuel delivery and ISC opening request would be for a cold motor.
so could a stuck or sticking TPS.
so could a stuck or sticking throttle valve.
a failing ISC will do the same.
NO codes for failing ISC.