Yamaha s225txrx. Had a lot of carbon built up on the o2 sensor. The motor would jump from 2200 to 3300 rpms without moving the throttle. Also was very hard to start. Once I cleaned and bench tested the o2 sensor and reinstalled, the motor ran great and started right up for about 3 mths. Now the motor has a lot of oil in the chambers. The spark plugs and o2 sensor fouls out with oil all over them. I did a sync and link on the throttle body. Checked the tps and crankshaft position sensor. Adjusted the oil link rod. It was still set at the original break in from the dealer. Checked spark and compression. All good. The o2 sensor bench tested good. I checked the spark plug boots and some where out of spec. I would think if those are the problem then it would be isolated to the cylinders that the spark plug boots where out of spec. Not all the cylinders. The motor still fires up great but shakes at idle and while increasing rpm. Also at top end the boat goes 44mph. The motor will lose a few hundred rpms and drop the speed down to 39 mph until you back off then it sometimes goes back to wot. The vst maintains pressure even when the issue occurs. It also has bean cleaned. The lp fuel pumps where replaced because of one leaking. Replaced spark plugs as well. Still runs rough and shakes at idle. I pulled the fuel rail and inspected the injectors. Looks clean and good. I don't know why there is so much black oil on the piston heads and the chambers as well as the spark plugs and the o2 senor. I have a d.v.a. coming in a couple days to test the stator. Im lost on the cause of excessive oil.
Thanks for any help
Thanks for any help