So i just bought a 1979 Crestliner Muskie 550 15' boat. It has an old Mercury 900 90hp outboard on it. Also i am a first time boat owner, anyways so my question is the motor wont trip up when i press the trip up button. It trims down just fine and when i press the "trailer" button it will trim all the way up but as far as the trim up button goes on the throttle it will not go up. I have not launched the boat yet i have just been playing with it in my driveway. Just want to be sure that the motor will trip up when i get on plane out on the lake. I suppose that i could trim it up with the trailer button but that seems kind of inconvenient as it is not on the throttle. I was thinking maybe the trim up button only works with the motor running or maybe when it is in gear? Any thoughts?