I had previously posted my Yamaha 2001 !50 HPDI model # Z150TXRZ wouldn't start. With help here I found the check valve between the filter and vapor tank was stuck. Someone said just get rid of it. The engine started right up and idled fine. After launching the boat I find it will start and idle, but when I bring it up to speed, after3/4 throttle it will start breaking up so bad it will stall if I don't bring it back to idle. Then I have to idle back, sometimes stalling even then. Always starts right up after stalling. I have put a pressure Gage on the vapor tank bicycle valve, and the electric pump has a constant #50 pressure during all times. Changed spark plugs, unhooked the throttle position sensor to see if it missed it, it did so I assume it's working. Are there any other sensors so critical it could cause this? Note the engine ran fine when I put away in the Fall. At that time I drained the vapor tank and fogged the engine.
