last year when i would trim my outdrive under power it would creep back down to the stop quickly, also when i went to trailer boat home for winter i lifted the outdrive up and it kept creeping down so i tied it up for the ride home, over the winter i replaced the trim pump and all was working perfectly, trim would stay up and no more creeping back down, i put boat in the water and trim is fine, working perfectly, the only problem is when on plane i cant trim outdrive, i hear pump working but outdrive will not go up, when i slow down and not on plane the trim works perfectly so i been trimming to where i think it should be then throttling up to planing speed and underway i can not adjust up only down this is a PIA and i want to fix it properly, my concern is i used a aftermarket motor/pump could this be the problem, i am stumped
