yamaha ox66 QUESTION

[Bitesomthing]

hELLO ALL:
I have a 2001 Yamaha 250 ox66 on my boat and it runs great at low Rpm
and in the mid range, i can cruise at about3800 rpm @24 mph but if i try to get up higher in the rpm range (4000-4300) the motor seems to cut out as if its starving for fuel( does not shut off) it acts as if you lifted your foot up and down on a gas pedal in your car.
My question is this, i noticed that the fuel filter on my motor is a 60 gph instead of a 90 gph? is this a flow rate that could cause this affect? I could use any suggestions on your thoughts.
Like i said it runns great til i try and push the motor?
Thanks
CHris

 

[Parker23]

VST filter maybe?

 

[jpg1969]

Based on the symptoms you describe (surging), I would recommend checking the VST pickup screen first. Here's more info on the subject:

http://classicparker.com/phpBB2/viewtop ... hlight=vst

 

[PaulH / Emily S]

Check the throttle position sensor. Likely your problem.

 

[Bitesomthing]

Yes the vst filter was all gunked up, i cleaned it up and started cleaning other filters, and now am thinking of rebuilding the fuel pumps.
thanks for the advice it worked
thnaks
Chris

 

[John_Madison CT]

Glad to hear you found the problem. The VST filter is often the culprit !!

 

[Parker23]

you can buy new low pressure pumps for about 35-40 apiece, I do not think it is worth rebuiding them in my opinion. just a few bolts and clamps(wire ties) good luck!

 

[Megabyte]

you can buy new low pressure pumps for about 35-40 apiece, I do not think it is worth rebuiding them in my opinion. just a few bolts and clamps(wire ties) good luck!

That is what I did last year... I replaced them on my 1997 OX66 and the increase in performance was instantly noticable.

My mechanic says that the fuel pumps should be replaced every 5 years or so, but that most people never even consider it. Apparently mine were overdue.

 

[Bitesomthing]

after a second trip out, with same problems after cleaning out fuel filter and
cleaning o2 sensor i decided to take boat to shop and have the pro's look at it. Well they came up with the fact that the High pressure pump went out and the Fuel injecters were about 90 percent clogged. ( thats going to hurt the pocket book.) well the tab is going to be about $1,500. To ease my mind i am going to put on new fuel injectors and have high pressure pump replaced. Even with this added price i stil can't compllain about the price i got for the boat.
Well if i dont tell the wife about these issuse i should be able to boat again sometime soon.

God how i love boats :wink:

thanks for all your imput
Chris

5-27-07
well after a few trips to the mechanic i think they have figured it all out, they called Yamaha and got a few answers, THE BRAIN of the motor was faulty and has been replaced. After 3 trips it still seems to run great. I hope prblem is solved.