2003 yamaha 90 2 stroke won't run at WOT sputters and loses rpms.

[Finfever21]

I was fishing today at the CBBT on my way there the motor wouldn't run at WOT it lost rpms and only would run at half throttle. I checked the primer bulb which wasn't completely flat but wasn't full either. After i squeezed the bulb it would run wide open then slow back down too half speed. I replaced the fuel pump,fuel hose, tank hose, checked all fittings, cleaned the filter and water seperator and still does it. Any ideas would be appreciated. thanks

[b8 boy]

Sounds like if the bulb doesn't get hard there is something blocking the flow at the pick-up in the tank. Do you have a flo-meter for your fuel usage? They get gummed up often. Has the fuel been in the tank a long time? Martin

[ChesapeakeBay]

What about the fuel tank Vent? Sounds like vapor lock.
I Recently had a racor filter that had an air leak in it and was sucking air from around the filter.

[schitty_vhull]

My vote is vapor lock also.

[Sushi Seaker]

Maybe borrow a 6 gallon tank from someone and run that if the connections work and if things are fine - you know the problem is somewhere in the fuel pickup system. Then start isolating back until you get to the gas tank - maybe sludge or ethanol contamination problems.

[Reid]

is it hpdi? sounds like vst strainer and pump filter needs to be changed to me, the strainer is about 80, the filter 30 and you will need a vst tank gasket for about 20 also.

[Scotsman]

150 hp and upwards for HPDI I believe. Its a pain, but easiest way is to run engine in water on aux tank as that will rule out a bunch of potential causes (see above).

H.

[BIRDDOG987]

Got the exact same motor, I forget the name of the part but replace the fitting that connects your fuel line to your motor. If there is even a little gap that can do it....

[Finfever21]

Sounds like if the bulb doesn't get hard there is something blocking the flow at the pick-up in the tank. Do you have a flo-meter for your fuel usage? They get gummed up often. Has the fuel been in the tank a long time? Martin

I do not have a flow meter, however the guy who had it before me had a problem with water getting into the tank and decided to leave the gas in their and run a above tank instead. I drained almost all the fuel out of the tank put fresh fuel and star tron in their and it starting acting up yesterday. I replaced the fuel pump yesterday ran it at city park and still did the same crap. I switched over to the portable and it ran fine. i replaced the hose that goes from the tank to the seperator last night and haven't had a chance to run the boat to see if it was fixed or not. fingers crossed i hope it was a bad hose leaking air or something.

[Finfever21]

is it hpdi? sounds like vst strainer and pump filter needs to be changed to me, the strainer is about 80, the filter 30 and you will need a vst tank gasket for about 20 also.

Its not a HPDI but thanks for the heads up.