Mercruiser pre alpha outdrive will not trim down

[bayslayer]

I am working on two 1971 Mercruiser pre-alpha outdrives they will not trim down and I am wondering if there is a safety switch that I am missing I have no switch is wired in the system now

 

[alldodge]

I am working on two 1971 Mercruiser pre-alpha outdrives they will not trim down and I am wondering if there is a safety switch that I am missing I have no switch is wired in the system now

Does the motor run when you push the down button?

http://web.cemr.wvu.edu/~mathews/boat/pdf/manual/Chapter Eighteen.PDF

 

[bayslayer]

No the motor does not run when I press the down button. It runs great going up but nothing down. I looked up the wiring diagram online and all of the wires are connected to the solenoid properly. I do not have the limit switch hooked up because there is no longer one on the boat

 

[wrench 3]

You need to find out if you have power to the blue wire at the pump when the down button is pushed.
Do you have one or two solenoids on the pump? 1971 I'm thinking "one" but would like to know for sure.

 

[bayslayer]

One solenoid. I will respond back when I get help pressing the button while I check for power. Thanks for the help

 

[bayslayer]

I have power to the blue wire right hand side of the solenoid opposite the red power wire when the outdrive is coming up. From what diagrams I have found the green wire is the down and I have no power to the green wire while the button is pressed.

 

[Bondo]

I have power to the blue wire right hand side of the solenoid opposite the red power wire when the outdrive is coming up. From what diagrams I have found the green wire is the down and I have no power to the green wire while the button is pressed.

Ayuh,..... Sky blue is Up,.... Green grass is down,....

 

[bayslayer]

I ran a jumper wire from power to the green wire and the outdrive went up. So it trim's up with the blue and green wire. Like I said previously as far as I know the wires are landed properly per the diagrams I found online.

 

[bayslayer]

Is there a check valve inside the system that could be stuck in the lift position?

 

[Bt Doctur]

take a #12 jumper wire from the + battery to the green motor wire, motor should run . Power comes from the small red wire at the solenoid. It supplies 12V to the trim buttons. If the "up" is working you have 12V power to there ,so start looking for a bad connection back to the plastic connector at the pump body.

 

[bayslayer]

Ok, I did jump the green wire and the motor does run but it runs the outdrive up instead of down. I will look for a bad connection.

 

[wrench 3]

Sorry for the mix up on the wire colors. I guess our off season is too long up here. Got to remember to retrain myself in the spring.:embarassed:
Do you have the two blue wires on one terminal of the junction block and the two green on the other. If the black wire from the pump motor is grounded, power to the blue wire should spin the motor in one direction and power to the green should spin in the other.
There are valves in the bottom of the pump. The only idea that I can come up with there is, if the slide valve was stuck and not opening the return check ball in the up side. MAYBE the total increase in oil volume MIGHT extend the rams even if the motor was pumping in the down direction.

 

[Bt Doctur]

so jumper the blue motor wire and see if it runs and goes down

 

[bayslayer]

Both blue and green wires make it come up. There is a block on the right side of the solenoid on the pump case that has the two green wires attached together, one comes from the motor and the other comes from the controlls.

 

[wrench 3]

You do have a problem with the control switch or wiring for the down side, Check the green and the supply at the down control switch for juice to isolate the problem.
As far as the motor/pump goes. I'd disconnect all three wires coming from the motor. Then with booster cables or the like, connect negative to the black wire to the motor and positive to the blue and then the green. If the drive still goes up both ways, it sounds like the pump is bad.

 

[bayslayer]

I just found time to check power to the wires. I found that the green wire has power at the switch when pressed but does not activate the motor. When I can a jumper to the blue and green wire they both run the pump but they both make the outdrive come up.

 

[Bt Doctur]

When I can a jumper to the blue and green wire they

you jumper from the + battery to the blue ,drive goes up
you jumper from the + battery to the green, the drive goes down
if this does not happen, the motor may be bad
The up power is controlled by the solenoid because the "up pressure" needs more amps to operated, going down it dosent and thats why there is only 1 solenoid.
The newer unit do have 2 solenoids

 

[Bt Doctur]

If both system are doing the same thing then their wired wrong or your testing procedure is incorrect. follow this diagram

 

[bayslayer]

I took the pump apart and put power to both the green and blue wire . The blue wire runs the pump counter clockwise the green wire runs a pump clockwise so looks like the motor is good. I will look into the above wiring diagram and see what I can figure out thank you to all for the help

 

[wrench 3]

If the motor is changing direction but the out drive is still going in the same direction, it looks like the valving in the pump is the culprit.
Now there is bad news and bad news. While I have disassembled those valves when I was young and foolish. They are a #&@ to work on and a successful outcome is not likely. Secondly that pump is no longer serviced, so you have to either upgrade or find a good used one.