'87 Merc 35hp Wiring problem

2fs2ns

Cadet
Joined
Mar 13, 2008
Messages
21
Looking over the new pontoon I wanted to take the battery to the house and get it charged up. When I started taking off the negative side wires I noticed one had the sheathing melted on it, and had actually melted/cut into the plastic battery box.

I traced it to the outboard, on a screw post on the back of the motor by one of the spark plugs. Does anyone know what that terminal is? Why would it get so hot?

The wire it was in also contained a red wire that was wired to the screw post below it on the outboard, but was cut off on the other end by the battery. Any ideas?

Pic of the "screw terminals" on the back of the outboard. The black wire goes to the top screw, the red wire was one of the ones on the lower screw.
http://picasaweb.google.com/2fs2ns/PontoonBoat/photo#5177398433959998914

The red wire in the background is something else, you can see the cut off red wire at the base of the melted black wire.

http://picasaweb.google.com/2fs2ns/PontoonBoat/photo#5177398472614704594

Here you can see the black wire in the outboard case, it looks like it's melted as well.
http://picasaweb.google.com/2fs2ns/PontoonBoat/photo#5177398567103985138

Do you know what this grey wire is going to the lower unit?
http://picasaweb.google.com/2fs2ns/PontoonBoat/photo#5177398614348625410

Any suggestions? I'm going to probably try to find a mechanic near Justin, TX that can look it over and do the impeller as well.


Dan
 

bgolson

Recruit
Joined
Mar 14, 2008
Messages
3
Re: '87 Merc 35hp Wiring problem

I can't tell alot from the pictures, but it looks like someone tried to come back in and rig something. Perhaps a custom line from the alternator to recharge the battery. Maybe that's why it got fried. Maybe try locating it on a wiring diagram. You can find one for your specific model merc online. Good Luck!

Bishop
 
Last edited by a moderator:
Top