[usmckao]

MECHANICAL FUEL PUMP!!!!!!

I think I have your fix. Had a 1987 Chaparral with an little 4 cylinder OMC that did the same thing, crank it driveway, run great on lake, but after it got good and warmed up it would bog down as if it's starving for fuel and eventually would die. Couldn't crank back up until the motor cooled off. Had numerous boat mechanics tell me it's either 1- anti siphon valve located near tank was sticking, 2- dirty carb, 3- spark plugs/wires.....they had no idea. I rebuilt carb---> no change. Did tune up to include plugs, wires, distributor cap and plug---> no change. Anti-siphon valve was clean---> no change.

It was the fuel pump. OMC motor had a mechanical fuel pump and when it got to operating temps, sludge inside would cause a blockage of fuel to carb. Replaced fuel pump with ease and boat ran like a champ!!!

[ColoradoDiablo]

His boat has electric fuel pump.

[uselessgrant]

I've been thinking about fuel pump, however my new ignition made huge improvement.but now it will stall sometimes when at wot trying to plane out. Holeshot is awful also.