2006 75 hp elpto serial no. 1b244674 power tilt trim problem

[barefootpoppy]

My power trim won't hold the motor up on acceleration. It drops right down. Mercury Marine USA told me it's probably a bad seal in the assembly. So instead of a rebuild. I purchased a new oem assembly and installed it. It still drops down upon acceleration. They are baffled. Told me to get a diagnostic from a dealer. 100.00 bucks per hour where I live. I tried an experiment I put the motor up where it should be when on plane at wot. I disconnected all electrical components ie. the power and trim sensor. It still drops down at acceleration. Almost 900.00 bucks in already. Any help before I break the bank again? Please?

 

[barefootpoppy]

Also I didn't mention. I checked the manual release screw it is tight. I did bleed all air out of the unit and made sure it is full when the motor is all the way up. I have the factory manual. Not much mention of the sensor. Except to make sure it's positioned properly at install. Should I try a new sensor? I don't know what it does. But a whole lot cheaper then the dealer's fees.

 

[barefootpoppy]

And the trim tilt buttons all work fine. One at the front of the boat one on the throttle control and one at the motor. On the trailer this assembly works great. I picked me and my son off the ground with the trim hydraulics. He's 6'4" 275 and I'm 6' 250. Holds and won't drop. Just drops when out at throttle up.

 

[barefootpoppy]

third post already. might be a unique problem.