2001 200 ox66 fouling plugs

[skeeterzx200]

2001 200 ox66 missing at idle, replaced plugs, 1 looked extremly fouled, ran great for 10 min, shut off started back up and missing again, clears up a little at 3500+ rpms but will just shut down after about 1 min. restarts fine but still misses, as far as i know the o2 sensor has not been replaced, possible fuel pumps? any suggestions before I go into a long detailed inspection process. thanks,

[boats.net]

If the plug is fouled again then check the fuel pumps. See if you can tell which cylinder has the fouled plug.

[skeeterzx200]

Thanks for the input, will try that again this weekend. I was not sure if a faulty fuel pump (leaking diaphragm) could allow fuel to enter the crankcase, also plan to clean the o2 sensor as I am sure it has been contaminated. Thanks again for the reply. skeeterzx200

[slim]

cleaning the o2 sensor is a touchy process if your going to do it right. its not just a matter of removing and spraying a chemical on it. you have to heatit with a torch in short bursts to burn the carbon and can permenantly damage the sensor very easily. so be careful.

[jb123]

just in case you may want to check your oil pump linkage to ensure it sits on the set pin on the pump, as it may have slipped at the 20 hr service.

[rangr02]

Skeeter, check the fuel pumps. They dont last forever and WILL allow fuel into the crankcase. They are vacuum diaphram pumps, leaking diaphram lets the fuel go right to the vacuum source- the crankcase. Normal life span of the pumps is about three years, they are fairly cheap and it is wise to replace all of them at the same time. If you dont know when they were replaced last, I'd replace them now and forget about them for another 3 years or so.

I think you are right about the O2 sensor being contaminated, you'll know when you pull it off the engine and see how bad its plugged. It sounds like you already know how to clean and test the sensor. If you dont, there is plenty of help here. Slim is right about being careful with that thing- they are expensive to replace so let us know if you have questions.