Smoked wiring harness

[buckeyeBEN]

What could cause the harness from the contoller/ignition to my merc outboard to melt and basically burn up?
This happened one other time due to loose terminal connections but they were tight.

Anything helps?
What Amp in-line fuse could I use to keep this from happening with a new harness?

Thanks all!

 

[Johnny]

This happened to my 1979 Johnson 25 when the starter
jammed up on the flywheel..... causing high amperage
to cook the wires inside the main harness. Plus, fried the starter.
and man-oh-man did it ever STINK !!!
This is when I did away with the quick disconnect at the motor
and ran straight wires from the control box to the motor terminal board.
That was probably not the culprit of overheating - just my choice to do so at that time.
I think a few things could be your culprit - just inspect everything using
the process of elimination of what went wrong. and how.

jus my Dos Centavos

 

[buckeyeBEN]

I know my starter is still turning over. It acts as if the kill switch has engaged. I'm chalking that up to all the melted bare wires.
Thanks for your input.

 

[DaleH]

Check carefully for signs of chafing or corrosion built up in the wiring. Runs should also be supported at least every 18" per ABYC standard E-11.

I've seen harnesses have issues, but most were shorting to ground, effectively killing the start circuit like an ignition kill.

DUMB question, but you don't by chance have a TON of keys on the ignition switch key ring, do you? Saw it happen once where the weight of the keys futzed up (technical term) the switch to where live contacts were making contact they shouldn't ...