2002 OX66 225 Fuel Starvation

[Reel Precision]

Weve got a Yamaha 2002 OX66 225. At around 4000 RPM the motor starts surging. I know it is due to fuel starvation because when you pump the ball while this happens it picks back up. We have ran it with the cowl off and the fuel filter/water seperator on the motor begins to lose fuel supply. We have checked all hoses with a hand pump and can draw a vaccum on the hoses without losing any great amount of pressure. We have replaced the ball. Any suggestions on where we are having the air leak or restriction.

 

[jim dozier]

Re: 2002 OX66 225 Fuel Starvation

I would look first at rebuilding the fuel pump. I don't know the particular pump setup on that engine but you are describing a failing fuel pump.

 

[rodbolt]

Re: 2002 OX66 225 Fuel Starvation

hello<br /> what jimd says. the pumps are about 45 apiece. I just replace them. you should have 3 low pressure pumps. they fail. they need replacing every 2-3 years.<br /> good luck and keep posting

 

[Reel Precision]

Re: 2002 OX66 225 Fuel Starvation

thanks guys. Yea I ran it yesterday on a remote tank and it did not surge but I could only get 4600 RPMs. (Before this fuel prob 5200) But you could see that fuel level in the water seperator/ fuel filter on the motor just will not stay up. Once you open it up the fuel level drops to about half of that filter. Is that correct? That is usually when it surges so I am assuming no. Anyway lift pumps are on order.

 

[rodbolt]

Re: 2002 OX66 225 Fuel Starvation

the water separtor on the engine will always be about 1/2 full when running. its just how it works

 

[Reel Precision]

Re: 2002 OX66 225 Fuel Starvation

thanks rodbolt. We replaced the lift pumps today but then beat our heads against the wall for three hours trying to find out why the fuel level drops in the filter. I then came in and then saw your post. We are going to run it tommorrow. I still cant figure out if the filter/seperator runs half full where does the air come from? It makes since though that the fuel must be tossed around in there for it seperate the water. I let ya know what I find. Thanks again

 

[Reel Precision]

Re: 2002 OX66 225 Fuel Starvation

OK replaced the three lift pumps, fuel check valve. Motor still surges at around 4700. You can pump the bulb and it picks back up. Also took the VST tank apart and cleaned needle and seat. The filter on the high pressure pump looked a little dirty but not like it would be the reason for the starvation. Any ideas? It is wearing me out!

 

[rodbolt]

Re: 2002 OX66 225 Fuel Starvation

have you cleaned and tested the O2 sensor? it will cause a high speed lean conditiuon if there is a problem.

 

[Reel Precision]

Re: 2002 OX66 225 Fuel Starvation

we cleaned it earlier in the year. How do ya test it? ANd would if that was it would the motor still pick up when you pump the ball?

 

[rodbolt]

Re: 2002 OX66 225 Fuel Starvation

hello<br /> by pumping the primer bulb you are bypassing the low pressure pumps. you are manually keeping the VST full. did you clean the vst filter? what kind of pressure is on the fuel rail? the o2 sensor has a test lead and the instructions are in the 2003 tech guide. if you can make the motor run ok by pumping the primer bulb I would use a vacum gauge and starting at the engine fuel filter look at see what fuel system vacum is at wot. it should be less than 6"hg max. I would rather see less than 4"hg. it is possible that you have a collapsd fuel line or a bad filter head someplace.<br /> just remember the primer bulb is only a pump. other than that it does nothing.<br /> good luck and keep posting

 

[Reel Precision]

Re: 2002 OX66 225 Fuel Starvation

Yes we cleaned the the filter on the electric pump in the vst. We cleaned needle and seat in the vst. we will check vaccum today. thanks rodbolt.

 

[Reel Precision]

Re: 2002 OX66 225 Fuel Starvation

Alright we cleaned the O2 sensor again and we reset the throttle position sensor to 5.0 V. Cleaned the VST tank needle and seat, filter. We ran it and all is good. The motor runs like it did before issues arose. A few questions though when tested the O2 sensor with Ohm meter it showed 4.7 Oms not .1 like the book suggested.