Doug is right on with the test thing, but being a Merc tech myself I would have to say that you could do the rebuild yourself lots cheaper than the the new pump if you only FOLLOW THE INSTRUCTIONS that come with te kit. Otherwise I'll buy your old pump cheap and rebuild it myself, then sell it to the next guy with this problem and give a guarranty on it. --- Jer

Mine was just the little 4 sided O ring in the pump. Bought the $75 kit just for the O ring and still have the kit with one spare. I looked everywhere for one of the O rings.

91 454Mag with Bravo 1 same problem..wasn't valves but replaced all gaskets in trim pump with kit..were all eaten away,,mechanics took a lot of time with diagnosis..can pressure test pump..by the way try moving drive up & down about 7 times to be sure no air in system after winter..SKY

ut oh!

Looks like beak boy is solo on this one.

I still think it's the popet valves. That is identical to what my Checkmate did. I'd set the trim and a few minutes latter the trim would have come back down. A pressure check would be the best way to diagnose the problem. A Merc mechanic told me to change the valves first because it solved the problem most of the time.

Dan