I have twin 1993 502 mags with Bravo 1's. My port drive will not stay up, will float down on it's own after 3-5 min of running. Also will drop some when sitting on the trailer. Can I just rebuild the up-pressure valve or should I just replace the whole trim pump? Where is best parts house to buy at? Tnks

Sure it's not leaking past the piston seal in the trim cyl.?

Have you tried switching pumps from side to side and seeing if the problem follows?

Used to be able to buy individual parts for the pumps. I have heard Merc no longer packages the parts individually. Check with BAM.

If your problem IS in the pump, it will be the check valve. On some pumps the up and down check valves are interchangeable. If yours is one of these, you can swap them fairly easy. The check valves on the offshore pump are not swappable, I have heard (but have never had to open one up).

ok thanks US1 and Mcollin...

Look also for hose leaks, especially on the trim cylinders and the connector block under the transom. Great advice from US1 and Mcollin...too.

will do tnks

were they disconencted and reconnected recently?

i had the same problem on my drive and i had them hoses connected backwards.

My money is on the check valves inside the pump.

A rebuild kit is available.

Pump was not disconnected. ck valve kit is like 50. so that might be the first to do.

Thanks for all your ideas

Swap the valves in the pump.You only need a hold valve in the extend mode.I had a problem with this a few years back.If you swap the hoses on the pump for test purposes and the problem goes away you know its the valve(trim switch will work in reverse).If you want to be lazy at this point swap the trim pump selenoid wires and your switch will work rite again.