100hp Mariner Trim Motor

[Deig]

I am having issues with my trim motor. When I give it a bit of throttle the trim motor trims itself all the way down. I am new to boating and have been told to run the boat it its optimum i should trim the motor up when giving it gas so the boat rides flat. At the moment as soon as i give it gas the trim goes all the way down and the nose of the boat rises way up. Any suggestions from anyone?

[Frosty]

You mean the nose goes all the way down?

Your trim motor is electrohydraulic, meaning an electric motor pushes oil into a ram that lifts your engine. When you give it gas it tries to push back the oil into the ram --If it can there is something wrong either no oil or the return valve is failing.

Checkl oil first thing,---get the manual out.

[Deig]

I have recently installed a new trim motor, drain the old out of the trim assemly and put new oil in. The engine is trimming fine when at slow speed though as soon I try a little faster it wont move. If i have it trimmed up a little then try accelerate it trims itself down. i will check the oil again tonight and test the level.

[Frosty]

Are you saying the old pump had the same problem and you replaced it and its still the same

[Deig]

No the old trim motor had water in it and did not work at all. We tested the trim with the new motor serveral times and it worked perfectly.