1989 Yamaha 90hp tilt problem

[codforbid]

I have a '89 Yam 90hp with a tilt problem.
It will trim up without any problem,until it reaches the end of the trim rams,then it stops.
The main tilt ram doesn't seem to be filling with hydraulic fluid.
I've taken the PTT unit out and put it in a vice and I can get it to tilt right up,but I can push the main ram back down by hand.
I've got a manual but it doesn't shot the ptt internals very clearly.
I'm wondering if the problem could be in the shock absorber valve or check valve in the main tilt cylinder?
Any ideas?

 

[durban]

Check the veins in the pump or the main ram seal . seems like its not building up pressure .providing the motor has changed direction for the down stroke if all is in order. also check pressure release valve if you have one .

 

[99yam40]

not enough fluid to pressure up the tilt ram maybe

 

[durban]

1st thing to do check to see if the solenoid for the down stroke clicks in, there are 2 one for up & the other for down when you press the button for the down stroke if there is no power going in there suspect fault at the button or on either positive or negative wires going to solenoid .

 

[codforbid]

The solenoid is working 100%.
The engine will trim up until the end of the trim piston travel.then the motor carries on pumping bit the main tilt cylinder doesn't seem to be filling with oil.
The reservoir is full,it's been bled a 100 times.
It'll rise to full height with the PTT unit removed but I can push the tilt cylinder,but nut the trim cylinders,back down by hand.
It's like the fluid is just circulating through the tilt cylinder instead of pressurising it.