2002 Yamaaha 225hp surging

[boatsmar1010]

I have a 2002 Yamaha 225hp 4 stroke with 1100hrs. Last time out the port engine started to pulse RPM up and down with the throttle at a set position. It did not stall it just varied RPM from say 2700 to 3800 RPM but it did not have full power. With both throttles set the same, the port engine would increase in RPM and drop back down but the boat listed to port like there was no power. When I ran at about 2000RPM both engines ran together. Back at the dock, in neutral I ran the engines at 2400RPM for several minutes and the engines never missed a beat.

Any suggestions?

 

[rodbolt]

Re: 2002 Yamaaha 225hp surging

check the fuel rail pressure under normal load at the trouble RPM. best guess is a clogged VST filter.

 

[boatsmar1010]

Re: 2002 Yamaaha 225hp surging

I will try that. Thanks for your help.