Electrical issue 1996 Mercury 75hp

mav6759

Chief Petty Officer
Joined
Jun 25, 2007
Messages
489
I have an electrical issue that I need help with. I have a 1996 Mercury 75hp, I just got it after sitting for awhile. I tried to start it for the first time on Tuesday, but for some odd reason I wasn?t getting any power to any part of the motor. I kicked both tires and all of a sudden I got power and the motor started the tilt/trim worked (life was good). So I saw that the insulation on one of the tilt/trim wires were gone showing the bear wire so I wrapped them up. Tilt & trim was working fine, motor was working fine, (life was still good). Then yesterday, I try to raise the motor and the and the tilt/trim would not work, (no power) then I finally got power and the relays would only click. I tried to start the motor (no power), then I finally got power to the starter. (don't know how). Played around with it alittle more, the motor finally turned over and back to clicking. Checked all the batteries, they were up. My meter shows I?m getting power to the motor and tilt/trim, (12.6) This morning I?m still getting 12.6 to the motor. Now the motor turns over, but the bendix on the starter will not return home, it stay engaged with flywheel, but it turns the motor over. I tried the tilt/trim nothing, but I?m still getting 12.6 to the motor and tilt/trim. All I?m getting right now is clicking from the tilt/trim relays. Every time I disconnect the wires from the batteries, (to make sure I'm getting a good connection) I?m getting a spark like I got the wires crossed. (I don?t) I don?t know if this is a short or what, because I?m getting 12.6v?s.
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: Electrical issue 1996 Mercury 75hp

Really confusing, Mav. It doesn't work, then it works, then it doesn't work again.

Using a multimeter to look for input to high current motors like the starter and the PT&T motor can be misleading. You can read 12.6V (too high) at the input to a motor that has bad or weak connections to ground. When the motor is getting good current you will read somewhere between 9 and 11V.

I would start by removing, inspecting and carefully scrubbing all battery power leads and connections shiny at both ends, with particular attention to the battery ground (-) connection(s) at the engine and the batteries.
 

mav6759

Chief Petty Officer
Joined
Jun 25, 2007
Messages
489
Re: Electrical issue 1996 Mercury 75hp

You are not going to believe this, it working again. Everything is working like it was brand new. Tilit/trim and motor starts on first turn. Now I know I got a short somewhere either at the controls or on the motor. Do you know if the boats have neutral safety switch. I wiggled the control handle a bit and I can move it into gear without pressing the release bar. But that won't stop the tilt/trim from going. Either I have a Short somewhere or the boat is possessed.
 

NYBo

Admiral
Joined
Oct 23, 2008
Messages
7,107
Re: Electrical issue 1996 Mercury 75hp

The neutral safety switch is in the throttle control box. But, as you correctly noted, that wouldn't affect the tilt & trim. There could be multiple electrical problems in that box, so it sounds like you need to open it up.
 
Joined
Feb 17, 2012
Messages
2,906
Re: Electrical issue 1996 Mercury 75hp

under the cowling is a inline fuse pull that out and clean or replace it as it could be a poor connection which is why it works sometimes and not others.
 
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