Trim Pump Solenoid

[micscrk]

I have a 1992 Rinker 260 Fiesta Vee with a 454 Mercruiser. The DOWN solenoid on the trim pump stuck in the on position. Since I didnt notice that the trim pump kept running, the solenoid completely burnt up. I replaced the solenoid and payed closer attention to when the trim pump was running ( i actually got in the habit of bumping the trim switch on the control up after plaining out to make sure that it didnt continue to push down). After about 8 hours of use the replacement solenoid also stuck (this time i caught it before it burnt up). I am getting ready to install the 3rd solenoid in 1 month. What is causing the solenoid to stick?

 

[thrasher]

Re: Trim Pump Solenoid

Usually a sticking solenoid is the result of trying to switch too much current, the contacts in the solenoid arc over and that welds the switch closed. Either your solenoid is not of a sufficient current rating for your trim motor, or the trim motor is taking too much current.
Too much current can be due to an overheated motor (such as leaving power to the motor when it can't turn, ie when the outboard is fully trimmed down! as you described in your mail) or it could be that the bearings in the motor or hydralic pump are failing, causing more friction so the trim motor has to work harder.. There are probably other causes, but I can't think of them.

Gary

 

[micscrk]

Re: Trim Pump Solenoid

I am sure that the trim pump was overheating because the reservoir at the bottom started to melt (however, I am not sure if that was the cause or the effect of the solenoid sticking).

I have also had several people tell me that it could be the trim switch on the throttle control (and several have also told me that it is not). The mechanic at my local marina said that I pushed the switch to the UP position and that did not over-ride the pump running in the DOWN position, that it probably was not the switch. He felt that the solenoid was getting voltage from something else.

Just prior to me buying the boat 2 months ago, the prior owners had replaced the solenoid also (they replaced with a Sierra part). When that one went bad, I took it to O’Reilly and got another one (Sierra). I have since been told that Sierra parts are not very good (any truth to that?). This time I ordered a Mercruiser part just in case it had something to do with the Sierra solenoids.

How can I test to see if the trim pump is for some reason taking too much current (as you suspect) and is actually the CAUSE?

Thanks again for your help.

 

[wire2]

Re: Trim Pump Solenoid

The pump will overheat if left on, it isn't designed to run continuously.

After you replaced 1 solenoid, (possibly a bad one), it shifts the focus to the controls.
Is it a single switch on the control lever or the 3 Mercruiser buttons?

If a single switch, it CAN easily fail.
There's a tiny spring in there that can break, a small tab can break off the rocker, a silver contact can fall down, shorting the "down" connection.
I'd replace the switch.

In the meantime, buy a cheap back up car alarm and wire it to the down motor lead. You'll hear anytime it's on.