yamaha 225f

[rclausen]

I have a Yamaha 225 4/stroke,engine runs rough at idle & stalls at times,also hesitates off idle,fuel pressure holding at 40 # no codes present,replace all filters,cleaned & ck vst filter,ck all coils & replace plugs, engine has approx. 750 hrs,any ideas

 

[rodbolt]

Re: yamaha 225f

carefully check the ISC valve. you can manually meter idle air by covering the hose with your thumb.
a good sign its bad is check it with a temp gun, if it goes over 200 degrees odds are high its bad.

 

[rclausen]

Re: yamaha 225f

thanks for the info,performed isc cks & all ckecked ok,any thought on possible fuel injector resrtictions,also possible fuel volume,like I noted fuel pressure holding at 40#,any tests to confirm low pressure pump is feeding vst enough fuel.

 

[rodbolt]

Re: yamaha 225f

most fuel issues wont show up at low speeds. if the rail pressure is holding then obviously the lift pump is working.
the ISC can pass the test on the laptop yet be mechanically stuck.
have you tested the TPS voltage as well?
most times with a sensor failure the engine will idle about 1100, not always.