Trim Problems 120hp cruiser.

[paulywally]

Hey there, I thank you before you help me for the help, this forum is a life saver.

I'm working on a 1985 Mercruiser 120, friends boat, they complained that the trim would only work to go down, not up. I check everything out, replace the battery connections, charged the battery and this is exactly what it did. I jumped the solenoid to make it go up and it worked fine, so the pump and motor are fine.

I work at a mercury dealership so I have access to all of the service manuals but the serial number off of the drive is not readable, and when I look up by application none of the wiring diagrams match what the boat's wiring looks like.

At first all i could get was down trim. After jumping the solenoids, (up solenoid and down solenoid system) all I got was a click in the down operation and nothing in the up position. I jumped the trim limit switch now I get a fabulous clicking of the solenoids in both directions which has fixed the up problem. But now the trim won't work. Just some nice clicks.

I am good at most electrical and figured out the solenoids without a diagram (not by any means hard), I have the battery on charge, but I am doubting the clicks being from a dead battery, seeing as how all I did was trim the motor up and down a few times, (shouldn't kill a battery.) I will try to start it right after I post this to see if the battery is the culprit but I highly doubt it.

Connections are tight and clean.

Any suggestions??


Paul

 

[thumpar]

Re: Trim Problems 120hp cruiser.

Take a look in manual #6. It has 3 different pump types with diagrams for each. See if one matches the description.

 

[FatBear]

Re: Trim Problems 120hp cruiser.

Clean and polish every electrical connection from the battery to the solenoids and then on to the pump motor. Dirty, corroded connections drop volts and you only have 12 of them to start with. Don't forget the grounds and be sure to take the lug off of the starter and clean it while you are at it. Use some anti-oxidant grease when you put them back together. Corroded connections will drop a lot of voltage and are the most common cause of electrical problems that I have seen both in my older cars and in my boats. They are almost always overlooked and are the cheapest things to fix. Get one of those battery terminal cleaners and spin it until they shine. Use steel wool or green scotch brite on those round lug connectors. Don't take the tin off if they are tinned, buff them with some old denim or canvas and make sure they shine. Even if this doesn't fix your problem, everything will run better and the pump motor will last longer.

 

[paulywally]

Re: Trim Problems 120hp cruiser.

Clean and polish every electrical connection from the battery to the solenoids and then on to the pump motor. Dirty, corroded connections drop volts and you only have 12 of them to start with. Don't forget the grounds and be sure to take the lug off of the starter and clean it while you are at it. Use some anti-oxidant grease when you put them back together. Corroded connections will drop a lot of voltage and are the most common cause of electrical problems that I have seen both in my older cars and in my boats. They are almost always overlooked and are the cheapest things to fix. Get one of those battery terminal cleaners and spin it until they shine. Use steel wool or green scotch brite on those round lug connectors. Don't take the tin off if they are tinned, buff them with some old denim or canvas and make sure they shine. Even if this doesn't fix your problem, everything will run better and the pump motor will last longer.

Battery is at 14.2 volts. Engine starts in half a second of the key being turned. No voltage drop to connections on trim motor. Any ideas?

 

[Bt Doctur]

Re: Trim Problems 120hp cruiser.

have you check the neg cable connections? if it worked when you jumped it, then something happened between then and now. corrosion in the power cables or connections.motor went bad, brushes sticking.

 

[paulywally]

Re: Trim Problems 120hp cruiser.

have you check the neg cable connections? if it worked when you jumped it, then something happened between then and now. corrosion in the power cables or connections.motor went bad, brushes sticking.

Figured it out after taking a day to think on it, it always helps when you aren't frustrated!

I took the motor apart, and the bolt that has a nut on the top, also holds the motor ground tight right beside the brushes. This bolt was loose causing an intermittent ground. I wish I would have tested EVERYTHING with my multi meter before pulling the motor out of the boat.

Live and learn. Lol.

Paul
Thanks for the replies everyone, they help my brain to start thinking like it should all the time!