Logo
FULL SITE MENU

Tilt/trim problem

M

mjw0002

New member
I have a '92 mercury 150 blackmax with a trim issue. The trim works great at idle speed and trailored, but whenever the boat is underway my motor will not trim up. The motor will trim down while underway just not up. I have replaced both solenoids, but didn't resolve the problem. Please help!!!
 
Does the electric signal from the trimswitch reach the solenoids? Does the solenoids click? If not, you could have a trim wire problem in the throttle contol handle.
 
Does the pump labor while under way but can't go up? Very little pressure required to lower the engine vs. raising it. Have you checked the fluid level? IS there a remote up/down switch on the engine? If it works then the problem may be in the handle as Lenard stated...the toggle switch may be worn out.
 
Lenard said:
Does the electric signal from the trimswitch reach the solenoids? Does the solenoids click? If not, you could have a trim wire problem in the throttle contol handle.
Click to expand...

Everything works fine while at idle speed it's just whenever the boat is underway. So are you thinking there maybe a connection issue at the trim switch?
 
There is less pressure required to lower vs. raising but while underway you have the force of water and help from prop turning which should make it easier to go up while underway opposed to idle speed. I have not checked fluid level but I am going to do that today! There is not a trim switch directly on the motor but there is one at the back of the boat. So next time I am out on the water i need to have someone using the switch in the back of the boat just so I can elimate the possibility of having a bad switch! Do you guys agree that the trim motor is not the issue since it works fine in all
Other situations?
 
I have a 70 hp tohatsu with the same problem and I know exactly what the issue is. I dont know if it applies to the merc. My pump ran fine but wouldnt go up. There is a manual pressure release on the pump that you can turn to make the motor go down if need be. Inside there is a valve and seat with an oring. the seat is bad and I can no longer get one. I made one out of a piece of rubber. Anyway it works up and down good but will not lift under power. If I start out with it up it will slowly go down. Pressure forces the motor down under power. If you have that manual pressure release it may simply need to be tightened with a screw driver. Or that oring and seat may need to be replaced.
 
i don't think '92 mercury release valves have a seat. I think they have three orings on a tapered plug. As the orings slides into a cylindrical fluid passage it gets located between pump pressure and pump release. As you loosen the release valve the oring(s) pull back and allow pump pressure to escape. Typically, fully tightening the plastic release valve on a mercury causes damage to the system.
 
I'm sorry guys but how is this going to help my situation? I need the motor to trim up not down. The issue I'm having is that my motor will not trim up while underway--it trims down fine all the time. Please explain what I'm missing! Thnx
 
Do the test...if the rear switch makes the pump run then the problem is in the shift handle toggle switch.
 
mjw0002 said:
I'm sorry guys but how is this going to help my situation? I need the motor to trim up not down. The issue I'm having is that my motor will not trim up while underway--it trims down fine all the time. Please explain what I'm missing! Thnx
Click to expand...

it is your hydraulic pressure pump. the fact that it lifts and holds on the trailer eliminates your rams and pistons. Your pump no longer holds the same pressure as it used to. When you use the throttle, the prop pushes creates back-pressure and the pressure valves in your pump are popping open too soon.

The manual release valve is really just a bypass. Due to the way they are built in mercury trims your system would either bleed down or not operate properly on the trailer. Since it appears to work fine at idle then your manual release is eliminated.

It's your pump. It needs new springs, seals, and check valves. They are BUNA rubber and wear out after about 20 years. can't be helped. making hydraulics without Buna would be astronomically expensive.

unless .... somebody has been tinkering with the innards of your trim system. then maybe it just needs an adjustment.
 
Hey guys just wanted to let everyone know that my trim is working great now!! I found the ground wire for the up solenoid at a bad connection! Very easy fix thanks for everyone's help!
 
Back
Top