2006 Yamaha 225 HPDI looses power and gains it

[Lansdale]

I have a 2006 Yamaha 225HPDI engine on my boat. Here is the problem that I am experiencing. We took the boat out to the lake and you throttle it down it goes good then loses power then it gains power then it loses power over and over again. I can go back and squeeze the primer bulb in the boat will run good. I replaced The paper filter in the separator also the metal filter on top of the electric fuel pump. Also I replaced all six spark plugs. It continued to do the same thing after that. Has anyone experienced this problem and if so what could it be. I just ordered two low pressure fuel pumps that should be in any day and the little strainer filter that is inside where the electric fuel pump is. Please help me and let me know what I can do.I also ordered a new primer bulb because someone told me that the primer bulb could simply just be bad.

[yam911]

Pumping the primer ball will (should) keep the VST (Vapour Separator Tank) filled with gasoline. Which is the job of the mechanical lift pumps.

If continuously pumping the primer ball results in the motor now running well, I would guess that the lift pumps are not doing their job.

A bad primer ball (or other stuff) within the fuel delivery system can work against the lift pump and cause them to fail to do their job.

[acfire]

Mine was doing same thing ended up being fuel tank pickup in tank had disentegrated about halfway up and when fuel got close to 3/4 tank and boat was running down lake it would get air and lose prime. Just a suggestion yours may be something different but i replaced filters and low pressure fuel pumps before figuring mine out . Mine was 06 200 HPDI 3.3