Usually you hear the hydralic motor straining in that case. It sounds like
this guy is pretty savy and I'm thinking the pump motor is not running at
all. The i/os definately have limit switches in them so I would not be
surprised to find something like that in some outboard setups. Most of
these use a couple medium sized relays to activate the up and down because
it's too much amps to run through the switches on the throttle. It's easy
enough to jumper them with a starter cord and test. That bypasses any
safety switches in the circuit. If it works when jumpered then it's switch
or bad connection somewhere.

"BruceM" wrote in message
...
Trying to push against the thrust of the propellor fails. Is it a 3rd
party trim/tilt assembly or original equipment?
Might be designed for a 50HP motor


"Jack Goff" wrote in message
...
On Thu, 12 Apr 2007 23:38:52 GMT, Short Wave Sportfishing
wrote:

On Thu, 12 Apr 2007 18:25:10 -0400, Jack Goff wrote:

A friend who has a boat with an old Mercury "tower of power" 150 horse
outboard is having a problem.

When the motor is in neutral, it will tilt up and down as it should.
However, once put in gear and moving forward, the motor will only trim
down, but not up.

The motor has had a new (rebuilt?) trim pump installed, and the wiring
harness was replaced. This work was done to get it running and back
in the water after having been stored for years. The problem surfaced
when lake testing for the first time.

Is there some kind of lockout/limit switch that operates when the
motor is in gear that could be causing the problem? Only thing I can
think of is the helm control could have an intermittant connection in
the "up" switch circuit that quits when the control is moved to the
forward gear position.

Any advice or experience?

It would seem to me that if the motor trims up/down in neutral, but
only down in gear, that there is something wrong with the hydraulic
ram - maybe low fluid, bad internal seal or valve? As in can't hold
against the gear pressure?

Out of curiosity, I assume that it only trims down when the boat is in
forward - what does in do in reverse - will it trim up?

I can't answer that... I haven't been out in his boat. To be honest,
I know he's a pretty smart guy, and I assumed that he had tried some
obvious things when he told me about this.

I'll have an in-depth converstaion with him tomorrow. But he led me
to believe that it just doesn't tilt up in forward. It seemed that
everything else worked as usual. Including being able to tilt the
motor up and completely out of the water when in neutral. I'd think
that if the pump/valve/seals were bad, that couldn't happen. But I'm
no expert in this stuff... that's why I'm asking.