Mercury 800 Tilt/Trim problems - Won't tilt up. plus general question!

[MatcherMike]

Hi all,

I'm hoping someone can please advise me and help.

I have a 1980 mercury 800 with power tilt and trim that i am currently restoring. I have 3 dash control buttons, that are labelled from top to bottom, Up Up Out In. The power tilt trim has never worked and i am trying to get it working.

First off I have identified that there was no power to the pump! I have added two leads to the battery and now i get life on the in button. Pump needed oil and bleeding and now it goes down! yippe. Problem is neither of the other two buttons do anything (and to be honest i'm not sure what they are supposed to do!). I don't get any sound from the pump.

I have checked continuity between the switches and the 3 pin plug into the unit. All are ok. There is power to middle and bottom switch, and the top switch gets power when the middle is depressed.

I have removed the trim limit switch to ensure it is not depressed - there is an open circuit on this wire.

Can anyone suggest what i should check next please?

Which of the buttons tilt it up, and what do the others do?

Appreciate any advice. I'm enjoying my first boat and engine restoration and am looking forward to getting it in the water!!

Many Thanks in advance.
Mike

 

[aussieflash]

Re: Mercury 800 Tilt/Trim problems - Won't tilt up. plus general question!

Dont know your pump.It may just need bleeding.Try and follow wiring to engine and you will find Solenoid.Clean all connections to solenoid and try again.Could also be dirty switches and connections at dash end.
1980 800 ?? I thought 1972 was the last 800e,im probably wrong.
A pic of the pump will get a much clearer response.

 

[Moody Blue]

Re: Mercury 800 Tilt/Trim problems - Won't tilt up. plus general question!

Here is a link to the manual for your PTT system.

Picasa Web Albums - Smig - PT&T Manuals

Here is a wiring diagram for your system. Yours may differ, in that some systems used two solenoids instead of one.



Upper button is to trim motor up. Bottom button is to trim motor down. Middle button AND upper button is to tilt motor up for trailering or shallow water operation. Pressing the middle button bypasses the trim limit switch allowing the motor to trim up beyond the "safe" operating range.

 

[MatcherMike]

Re: Mercury 800 Tilt/Trim problems - Won't tilt up. plus general question!

Thanks both,

I'm sure the pump needs bleeding - it did on the cylinders controlling the down tilt, however when pressing either of the up buttons (or both together) the pump doesn't even make a sound so i'm suspecting something electrical.

Moody Blue has it spt on with the diagrams and manual. Many Many thanks that's fantastic. Mine is exactly as shown with a single solenoid. The wiring now makes so much sense!

Sadly it doesn't nail down my problem! I'm certain continuity is good to the 3 pin plug from the dash switches. I'm also certain the switches work. I can eliminate the trim switch as pressing both together doesn't work (which i now know bypasses the trim switch). I can only guess that the wiring from the solenoid to the pump could be faulty. I'll have to check this.

How do i eliminate a solenoid fault? Would the fact the down works mean the solenoid is good? I guess it could be the pump itself?

Many thanks for your help thus far
Mike

 

[Chris1956]

Re: Mercury 800 Tilt/Trim problems - Won't tilt up. plus general question!

Jumper power from the red battery wire to the blue wire at the red 3 wire plug. You can do it from the vertical slot on the red plug to the upper horizontal slot with a wire and two spade crimp on connectors. if the motor spins, it is good. That means the wiring is bad. Did you connect the two wires that went to the trim limit switch? You should, to eliminate the upper pushbutton.

If the motor spins and the motor won't trim/tilt, bleed the up portion of the cylinders. Next to where the up hoses connect is a bleed screw. It must face up and be removed. Now run the trim up and wait for all air and air/oil to be expelled. Repeat with the other cylinder.

 

[aussieflash]

Re: Mercury 800 Tilt/Trim problems - Won't tilt up. plus general question!

As I said before...clean all connections including ground on solenoid (shiny clean)....wire end and terminal.May also need to clean switch,as i had to.
My trim has broken down twice in 3 years...first was dirty switch...second time was dirty connection at solenoid....simple fix.If still not working just run another wire direct from switch to solenoid to eliminate bad wire.