Strange, but here's the story. <br /><br />I have a 40 hp '97 Yamaha The tilt trim works GREAT when the motor is at rest, ...up and down all day long. It works GREAT when the key is on and the boat is in the water ...up and down all day long...Also, It holds its raised position if I leave the motor raised up all night long!!! <br /><br />but..... <br /><br />When the boat is under way, even moving very slowly, it will go down, but it won't go up . It tries. I can hear and see the hydraulic shaft trying to raise the engine. It doesn't seem to have enough power, even at very low speeds??? <br /><br />My mechanic, ( by phone, from 1200 miles away ) suggested I try <br /><br />1. bleeding the system ( I did..to no avail) and <br />2. check the "bypass".... (I don't know where the "bypass " is).... to be certain that someone didn't leave it loose.. He couldn't sufficiently describe it's location over the phone. I did find an Allen wrench ( metric) fitting in the cylinder area, but it was very tight. The motor is mounted on a manual jack plate, so it is possible that I cannot see the bypass without pulling the engine from the JP. ??? Anyone know where the d%%#$# thing is??? <br /><br />I don't want to bring it to an unfamiliar dealer here ( Lake Geneva, Wisconsin) since I know they are all backed up and I don't want to be with-out my boat for three weeks right now. <br /><br />Any ideas? If I had to guess, I'd think that the voltage to the t/t motor is too low... when under way. I checked (looked at ) the connections, and they look great inside of the engine. I did NOT take any voltage measurements, but will if some one thinks that might tell me something useful. <br /><br />Any help or advice appreciated. Thanks RichG