Melted 8n wiring harness

FordNMan · Feb 27, 2018

Just got finished converting my N to the 12 v and i took it for a drive around he yard when al off a sudden a small fire broke out on the wiring harness and smoke came bilowing out. I turned the key off and ran like a bat out of hell for an extinguisher. By the time I got there the wires melted and the fire went out. I had notice the ammeter was acting funny. I’m thinking he ammeter shorted out but the harness meted right next to a spark plug as well so either the spark plug shorted the harness or the ammeter. Just wondering if I need a new ammeter or not? Definitely going to make some brackets on the head to tie the harness up to

Bruce (VA) · Feb 28, 2018

Front or side distributor?
75 Tips

FordNMan · Feb 28, 2018

(quoted from post at 05:16:39 02/28/18) Front or side distributor?
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Front Dist

Bruce (VA) · Feb 28, 2018

All of the wires, including the plug wires, should be in the conduit on top of the engine. Were they?
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FordNMan · Feb 28, 2018

I think that part of the problem is there’s no conduit

Dollar Bill · Feb 28, 2018

I think that part of the problem is there’s no conduit

Not necessarily. The conduit was dropped with the addition of the side mount distributor.

What caused the problem is B+ found an unintended ground causing a short circuit. Current flow increased turning the wiring into a heating element.

Is it possible something shorted out on the back of the aftermarket amp gauge or maybe the resistor?

FordNMan · Feb 28, 2018

The amp gauge is original

souNdguy · Feb 28, 2018

if the ammeter does not look damaged, test it against a known good one.. if it reads ok, use it. Unless it is an inductive type,
it will contain a shunt. as long as nothing was thermally damaged, it should still work. ammeters like that are really volt
meters anyway..just measuring the voltage drop across the shunt.. thus the term shunt-voltage meter.

Bruce (VA) · Feb 28, 2018

Get a conduit or wire it like sidemount w/ the wire loom for the plug wires.
75 Tips

Royse · Feb 28, 2018

In your [b:c2a5b9a865]other post[/b:c2a5b9a865] you said the ammeter was pegged all the way right.
You also said you drove it around that way for 30 minutes.
To me that sounds like the meter was working and either ignored
or the off the scale indication was misinterpreted.

Ignition, starting and charging are separate circuits.
It sounds like starting and ignition are working. You can run it
that way with the charging circuit disconnected to isolate where
the trouble is. If those two work fine, then work on getting the
charging circuit working. It'll run at least a month on a fully
charged battery before you'd need to recharge it again.
Unless your problem is in those circuits and I'd all but rule out
the starting circuit unless your starter was still spinning.

ASEguy · Mar 1, 2018

If it is original wiring, I would replace it all and cover the wires in split loom.

Roy Warren · Apr 3, 2018

I just now had the same thing happen to me. Finish 12v conversion yesterday. Started and ran fine around the yard, but ammeter was showing negative instead of positive.
So I read somewhere that I need to switch the wires. Disconnected the ground cable from the battery. Decided to lift the ammeter out so it would be easier to get to the terminals, but that didn't work so reversed the wires and tightened them down. Didn't put the ammeter all the way back in because I wanted to see if it would work first.
Was hooking the ground cable back to the battery when the smoke started pouring out. Jerked the battery cable off and waited for smoke to clear. Wires are fried.
After reading the replies to your post I think maybe the ammeter being loose in the hole, may have grounded out.
Any comments would be appreciated.

JMOR · Apr 3, 2018

(quoted from post at 10:59:47 02/28/18)
The amp gauge is original

ell, IF "original", then there is no electrical connection to such an induction type ammeter. But if not, then mounting is critical, so that terminals have no path to bracket or dash metal parts.

Melted 8n wiring harness

FordNMan

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Bruce (VA)

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Bruce (VA)

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