Yamaha F115TXRB wont idle

[rbriel]

I have a 2003 115hp 4-stroke, model F115TXRB that does not want to idle or run below 1800-2000 rpm's. The outboard runs great at any RPM above 2000.
When the problem first started it was intermittent and then became more common. Now it happens most of the time. It is worse once the engine becomes warm.

Anyone have any ideas as to why.

 

[rodbolt]

Re: Yamaha F115TXRB wont idle

I would test fuel rail pressure for low pressure,excessive pressure and leaking injectors.
then i would check the operation of the ISC valve.

 

[rbriel]

Re: Yamaha F115TXRB wont idle

I have never had a fuel pressure issue at idle or low RPM that didn't severly effect high RPM's as well. But I have never had to work on a Yanaha before other than an electical problem.
Is there a standard test for Idle Speed control?

Thanks for the input

 

[rodbolt]

Re: Yamaha F115TXRB wont idle

then you have never seen a leaking injector,rich at idle, a defective regulator causeing excessive rail pressure,rich at idle.
or a sticking ISC valve,rich or lean at idle depending on where its stuck.
standard ISC test is with the laptop and operate the valve manually.

 

[rbriel]

Re: Yamaha F115TXRB wont idle

Thanks
I will start here, hopefully an easy fix

 

[rbriel]

Re: Yamaha F115TXRB wont idle

JUST AN FYI
It ended up being a combination of the TPS and thermostat. Engine never getting to full oprating temp and causing TPS voltage to be slightly off