Re: 99 Yamaha 150 hp will not pump water
the 98-99 pumps had poor impellers. but it was only for those two years, those impellers will have a white plastic hub. what are the impellers and housings looking like when he is done? also check the rubber dam just aft and under the pump plate. if corrosion lifts it slightly it will give the same symptoms. I remove the dam and the metal bracket for cleaning/inspection on every pump job. if he is usuing the flush port on the engine with the motor running it will rapidly trash the impeller. if the housing is melted in the least it can cause loss of water pressure. a pressure contol valve that is hung open will cause a total loss of water pressure as well. if the pocket has not been cleaned and the grommet replaced I would look there as well.
