1989 mercruiser alpha one trim problem

[justabuck]

I have 4.3 mercruiser alpha one and need manual for trim troubleshooting. I am trying to figure out why the trim button won't engage the trim cylinders in either the trailer mode or by depressing the toggle switch on the quicksilver side
mount throttle. I depress the up on the switch and I hear the pump. When I depress the down switch I hear a click. I have siphoned all the fluid out and replaced with new. It was milky too. Any help would be appreciated. Thanks
The drive serial number is UC651520. 1989 chapperal 198xl Limited. 4.3 XL

 

[Silly Seville]

Re: 1989 mercruiser alpha one trim problem

Welcome to iboats!

We need more info. Is this craft new to you? The electric over hydraulic system for the outdrive is incredibly simple. There can be only one of several things wrong. Bad switches at the helm, bad wiring from switches to relays at the pump, bad relays, solenoids, loose connector, and the most likely culprit...bad trim sending units. They are on the bell housing and have two wires each. If the trim senders or their wires fail, the pump doesn't get the appropriate signal to perform. Tell us more about your ownership/maintenance of the boat and we can narrow it down for you.

 

[Don S]

Re: 1989 mercruiser alpha one trim problem

Here is the troubleshooting charts and wiring diagrams for your trim system.

View attachment A1,MR,RTrim Troubleshooting.pdf

 

[justabuck]

Re: 1989 mercruiser alpha one trim problem

Yes this boat is new to me. The boat sat for two yrs covered but not indoors. Motor runs great. The former owner is longtime friend. He stated that he thinks the problem is in the throttle control. I just need direction to start making the repairs. I am new to owning a boat and want to use my head instead of writing unnessecary checks.

 

[Silly Seville]

Re: 1989 mercruiser alpha one trim problem

A digital multimeter is your best friend! Follow the schematics and troubleshooting charts, and you will become an electrical diagnostician is no time!