1990 MercCruiser 4.3 Liter Alpha Drive doesn't Work

[truckermatt]

On my way to the boat ramp, before I left I tested and raised the outdrive to make sure everything was working (Everything was good). 30 minutes later when I got to the boat ramp, put the boat in the water and went to trim down nothing happened (no click in the solenoid, no clicking in the throttle switch); basically no sound at all just a dead switch.

I checked the inline fuse, and it still looked good by the pump.

Also the main engine circuit breaker was not blown either.

Throttle switch itself is good, because I tested for continuity.

I could not get a reading for power when I tested from the switch to the pump.

What is the next step that I should look at?
How do I go about taking the throttle box off to look behind there?

Thanks,
Matt :facepalm:

 

[Bt Doctur]

Re: 1990 MercCruiser 4.3 Liter Alpha Drive doesn't Work

You dont take anything apart yet.you troubleshoot it first.
main power cable connected, both pos and neg.
harness plug installed correctly at pump
12V power to solenoid buss bar
(connector bar).
using a jumper from the + battery , touch the blue wire(up) then the green wire(down) to see if motor works.

 

[Bt Doctur]

Re: 1990 MercCruiser 4.3 Liter Alpha Drive doesn't Work

http://www.boatfix.com/merc/Techbk/97/97hs6.pdf

 

[truckermatt]

Re: 1990 MercCruiser 4.3 Liter Alpha Drive doesn't Work

You dont take anything apart yet.you troubleshoot it first.
main power cable connected, both pos and neg.
harness plug installed correctly at pump
12V power to solenoid buss bar
(connector bar).
using a jumper from the + battery , touch the blue wire(up) then the green wire(down) to see if motor works.

Tried using a jumper, and nothing happened...

All cables connected normally, except the inline fuse holder, which broke, so i temporarily skipped the fuse and direct wired it.. Would that cause a problem?

 

[Bt Doctur]

Re: 1990 MercCruiser 4.3 Liter Alpha Drive doesn't Work

you used a jumper from the battery directly to the motor wires at the solenoids?
Nothing: negative power lead bad/disconnected or the motor is bad.

 

[truckermatt]

Re: 1990 MercCruiser 4.3 Liter Alpha Drive doesn't Work

Just found that the trim limit thing on the drive itself one of the wires is frayed off and the other almost.

Could this be an issue? I find it hard to believe that this broke 30 minutes after we just use the trim

 

[Don S]

Re: 1990 MercCruiser 4.3 Liter Alpha Drive doesn't Work

The trim limit switch will have no affect on down or if using the trailer button.

Did you jump from the battery to the green or blue wire on the large terminals of the solenoid to see if it would run? (Blue=sky= trim up) (Green=grass= trim down)

 

[truckermatt]

Re: 1990 MercCruiser 4.3 Liter Alpha Drive doesn't Work

The trim limit switch will have no affect on down or if using the trailer button.

Did you jump from the battery to the green or blue wire on the large terminals of the solenoid to see if it would run? (Blue=sky= trim up) (Green=grass= trim down)[/QUOTE

I took a piece of wire and held it on the positive side of the battery and then touched the blue and green wires, but nothing happened... I even checked with the voltmeter, to see if the wire (jumper) had power but the voltmeter said nothing.. Really confused now...

And I unplugged the 3 wire plug connector that appears to come from the throttle switch and hook into the pump.. I tested for power on al the wires and had nothing when pushing the trim button.

 

[Don S]

Re: 1990 MercCruiser 4.3 Liter Alpha Drive doesn't Work

Did you hook you jumper wire to the blue or green terminal on the LARGE terminal of the solenoid?

 

[truckermatt]

Re: 1990 MercCruiser 4.3 Liter Alpha Drive doesn't Work

I hooked the jumper wire to the terminal after I followed the wires directly out of the motor, where the wires ended when they came out of the motor.

Blue=nothing happened
Green=nothing happened

I even put it on the black ground cable coming out of the motor, expecting a spark which I read online; but nothing happened either.

I think that it may be the motor, but i would still expect it to be grounded correctly.
No connections are loose or disconnected.

Thank you everyone for your help so far.
Matt

 

[Don S]

Re: 1990 MercCruiser 4.3 Liter Alpha Drive doesn't Work

I even put it on the black ground cable coming out of the motor, expecting a spark which I read online; but nothing happened either.

That tells you the ground cable between the pump and the battery is defective. Either broke, corroded, not hooked up or whatever. But there is no connection to the battery.

 

[Don S]

Re: 1990 MercCruiser 4.3 Liter Alpha Drive doesn't Work

Do you have a 12V test light handy? And if you do, get it and post a picture or two of your trim pump.

 

[truckermatt]

Re: 1990 MercCruiser 4.3 Liter Alpha Drive doesn't Work

Here is an update, Once i replaced my corroded inline fuse, I notice a long thick gauge wire sitting near my bilge, I realized it was loose, So i followed it back to the trim pump and noticed the loose end was supposed to be on the rear engine ground bolt. I hooked it up and of course it works.

I want to thank everyone for their help, Unfortunately I wish I would have saw this at the boat ramp but oh well.