2000 Yamaha 225hp falling down between 5000 and 6000 rpm

[grappajoe]

My motor is is idling ruff and falling down between 5000 and 6000 rpm.I have drained and replaced the gas ,changed water seperator filter and fuel filters and replaced the fuel line in case of leaks. When runing at low rpm's3000 to 4000 the rpm's go up and do one or two degree's. I have changed all the plugs and one plug seems like it is not burning all the time its has some browness to it but is mainly clean while the other plgs are burning effectively.Please help is this a bad CDI or maybe a coil assembly I am stumped

[jb123]

what model ? efi ? if so,
sounds like o2 sensor, clean and test:


http://www.boatsetup.com/O2sensor.pdf

[grappajoe]

It is a model sx225 txry on the cauling it says ox66fi I kn ow it is fuel injected,Where do I find the O2 sensor I do not have a manual for this motor. Many thanks grappajoe

[crayman]

Grapajoe I have CD workshop manual can email it to u check my post to Bigshy re ur prob
Maurie

[flytact]

Do a search for vapor separator tank - VST. I don't remember if I found it here or on another engine forum, but there were good directions. Basically there is a filter in there that is most likely clogged, starving the engine when you demand more. It was an easy clean, you will however need a new, expensive gasket.
Try this link:http://www.thehulltruth.com/forums/t...=91869&start=1

[slim]

its not the filter in the vst tank. rough idle wont be caused by o2 sensor but will cause cutting back over 5000. this motor only idles on cyl"s 1,3,4,6. so it wont be hitting on them at idle. do the o2 sensor check first.