engine bogs on accelleration

I have a 2004 yamaha 200v6 efi. when i try to accellerate, the engine bogs and falls on its face. I have to accellerate slowly to get on plane but can not go more than half throtle until it bogs down. I have changed plugs, fuel filter, and switched to non ethanol gas.The plugs are wet with fuel when I check them. The primer bulb gets hard and does not loose pressure. Any suggestions???

[jb123]

sounds like a bad low pressure fuel pump, unbolt them, pump ball see if gas comes out of vac port,if so, replace.

engine bogs

Thanks for your info JB. I hooked up a fuel pressure guage and ran it for 1 min. The pressure was around 35psi at idle and it did not change when I lightly reved the engine. Is that normal or should the pressure change when when I give it gas or does that confirm your answer? I'm great with cars but a little unsure where the low pressure fuel pump is located on this engine. Any pointers or recomendation where to get a repair manual at a local store?

[jb123]

the lp pumps are after the motor filter, prior to the vapor separator tank.

easier to remove the 3 vst mount bolts to access the upper lp pump, just move the vst to the left a bit to access lp pump bolts, 2 - 10 mm on each. unbolt, leave hoses intact, pump ball and if gas comes out of back, the lp pump is bad. reinstall with new gaskets.