I have a 1996 or 1997 J150EXEDB 150 Hp ocean runner. About 8 months ago i started experiencing what i thought my have been cavitation but this weekend it became apparent that it is not. Before when running cold the engine ran GREAT. After getting hot it would run to 4500 rpm fine anything more the engine would hesitate/shutter you let off the throttle back below 4500 and it was fine. This weekend while running my buddy had pushed in the choke/primer while running and the water temp light came on after bogging down a little which would be expected when priming a warm engine. I shut the boat down to make sure wasnt running hot and appeared fine, however, upon restarting it would run great to 2400 rpms and nothing more could not even plane out. After getting back to ramp and inspecting i noticed the Primer/Decarb vavle had a crack in it and would actually leak when priming the engine? Could this small leak be allowing air to mix with the fuel causing the problem and if so When we primed at full speed could this have allowed even more air than was already getting in and caused this to happen. When it did go down to 2400 rpms any throttle amount over that made the engine shutter/hesitate and the whole boat shook with it. The following day i took it out again in hopes of it just being the valve and sure enough as it has in the past it ran great when cold. I have a new valve already on order. It needs replacing for sure anyways. Any suggestions? Thanks, Scotty
