Outboard motor won't trim up while boat is moving?

Question

It won't go up while moving and with it up about halfway at the start it will drop down. Is that air in the line or other. Also, when parked on trailer I put the motor up all the way and it slowly goes down.

Answer 1

2 things  first trim the engine all the way up and lock it in remove the fill cap  fill it to the top  put the cap back on and go up and down a few times and check it again with the engine up also you might have a leak somewhere only put oil in the up position

Answer 2

What make and model?  If Merc, sounds like  the seals are gone in the pump.  This is a pricey repair, you might consider looking for used, or a parts motor.  Have you checked the fluid level, trimmed up?

Answer 3

Your seals and o-rings are going bad inside the trim cylinders and allowing fluid to bypass out of the cylinder back to the reservoir allowing the motor to drop. Have the cylinders resealed or replaced.

Answer 4

Haven't had this motor very long, eh?

First, I need to know, what make, year and hp we talkin bout here?

Go round and take a look...how many pistons do you see on your motor bracket, is there one, or three?

This isn't the solution to your problem, but you really do need a "transom saver", unless you have plenty of clearance under the skeg with the motor fully down on the trailer.