99 Yamaha OX66 - 225 no power at high speed

[sgstrick]

I have a pair of Yamaha 225 OX66 on a 28 Pursuit and the port engine has started losing power above mid throttle. The starboard engine runs great, but the port has had a history of issues - found a fine sediment in the fuel tank, cleaned it out, cleaned out the high pressure fuel pump, changed fuel filters and it fixed the fuel clogging. this year the motor will run up to about half throttle, then it does not have any power and does not respond to the throttle. Any ideas on how to track down this problem?

 

[SparkieBoat]

Re: 99 Yamaha OX66 - 225 no power at high speed

those engines can be challenging to troubleshoot...first of all..I would not run the motor if it is acting up, you could have a lean conition and pop a piston. .. You said you fixed the fuel clogging...what does that mean??? sounds like you you need to send your injectors off to be cleaned and flow tested..I heard they charge about $20 per to do this. I would do both motors..I know a yamaha master Tech that said those VST chambers need to be cleaned out yearly. and there is a filter in your high pressure fuel pump that i have heard others say that they removed..http://www.yamahaoutboardparts.com/forum2/filter-screens-hp-fuel-pump-th15519.html#post57133

 

[sgstrick]

Re: 99 Yamaha OX66 - 225 no power at high speed

The fine sediment in the fuel tank kept getting past filters and into VST - after 3rd time, I learned to clean the VST chamber and change the needle valve. I have cleaned the VST filter on the high pressure fuel pump. As far as cleaning the injectors, are there six injectors (one per cylinder) and where do you send them for cleaning/flow testing?

 

[SparkieBoat]

Re: 99 Yamaha OX66 - 225 no power at high speed

I forget where..start a new thread with that question...someone will tell you.I think the cost is about $20 per injector...I am thinking that there is another filter in the high pressure pump besides the one on the bottom..I saw some pics of it the other day but I cannot remember where..they said they just removed the filter because yamaha did not offer a replacement

edit; it was on a HPDI..not sure if your fuel pump is the same. here is the link
http://www.yamahaoutboardparts.com/forum2/hpdi-mechanical-high-pressure-pump-th10974.html