miky2884
Well-known member
I decided to do some routine maintenance on my 2000 225 ox66 this weekend.I have no idea when and if any maintenance was ever done on this motor prior to my buying the boat last year so it was time. At the end of last year I was loosing RPM's at WOT and I was hearing a sputtering in the engine when at WOT. The motor also ran a little shaky at low RPM's. I had done my research and all signs pointed towards two things fouled O2 sensor and clogged VST filter. Well upon pulling it apart I found that both where pretty bad (see pic below) When we took the O2 sensor out, out came a lot of carbon build up behind the sniffer tube and the O2 sensor was pretty black. I soaked the O2 sensor over night in Yamaha combustion chamber cleaner along with the elbow piece and then scrubbed both the next day with a tooth brush to bring the O2 back to normal color and clean all the carbon build up out of the elbow. Changed out the VST filter with a new filter and replaced VST tank gasket. I have not ran the boat yet but I did start it in the drive way and it ran 100% better, kicked up between 12-15 RPM and then when warmed up kicked down to between 6-8, this is something it was not doing last year it would race upon start up. So im hoping these to fixes took care of my problem im pretty confident it will. All in all changing the two where not to difficult, I will clean the O2 sensor every year now.
