have a 92 75hp merc outboard. the problem that just started last time i was out is that the motor, when over half throttle, looses fuel pressure, the priming bulb goes soft and the motor wont run. it works fine in trolling speed or when someone is in the back priming the bulb while at full speed. im thinking mabey an air leak in the hose but not sure cause there is no fuel leakage? anyone got any ideas? im pretty knowledgeable about the mechanic side of things but this ones got me stumped.