Hello all, I know this topic has been covered time and time again and I just went through 15 pages of the topic and still nothing seems to fit.
I have a yamaha 250 ox66 motor that was recently rebuilt and hasn't run right since. (rebuilt because water got into the oil) It is bogging down on take off and not reaching top speed. Only getting about 5500 RPMs out of her. I should mention that I had the fuel pump and fuel regulator replaced 6 months before the rebuild and it never reached top speed after that but did run smooth. Have since taken it to a different mechanic than the one that did the rebuild. First thing he did was leak down and compression test, tested like new. He found a pinched fuel line and I had him replace all fuel lines, filters and all, also LP fuel pumps checked the VST, etc and replaced the O2 sensor, not cleaned. Then I tested it and it was still bogging down on take off and not getting past 5500 rpms and even dropping down to 5200 rpms. Took it back to the shop he pulled the injectors and sent them for a flow test and two tested bad, fixed those. (this was supposed to have been done with the rebuild but somehow didn't get done) Tested it on the water today and the problem isn't nearly as bad but it is still bogging down while getting up on plane and still wont go past 5400/5500 Rpms and still drops back and forth to about 5200 rpms. Mechanic said TPS bench tested fine. Thinks maybe the strator now but thats his best guess at this point. Can the TPS test good but still be bad? Can the REV limiter cause this? Any suggestions will be greatly appreciated as I am now several thousand into this and he is many hours into it as well and surly getting frustrated.
Thanks in advance for any and all replies