Ignition Connector Plug melt

[76 FJEID]

I recently bought a 76 FJ40 with a 350 engine swap and fired it up and ran well the first 2 test runs. Third test drive I noted a tiny odor in a 10 minute drive which I assumed was engine oil burning off a recent oil change. Parked and then the next day and when I turn the key the starter solenoid is on but, the starter does not engage to fire the engine. Checked battery and all good, tried starting and tapping the starter and wouldn't engage, so I traced everything back to the ignition wiring harness and the BW wire into the 4 pin connector. Again, new to the car and didn't inspect every wire prior to driving but, I assume this was the "odor" from a melted wire from the ignition switch to the 4 pin connector to the starter? From what I have read that melted wire connection could very well reduce the current enough so the solenoid will fire but, not enough to engage the starter? I have a new 4 pin connector coming but, trying to understand what may have caused the wire to heat up so much to melt it and want to address that too and if there is a way to test the starter without pulling it out by simply running a wire directly from the BW ignition pin to the starter itself?

 

[Engineer8000]

Your fuses or fusible link are not working, you should not get a melted wire in the harness if they were. I would investigate that also.

 

[45Dougal]

Some corrosion built up in the connector can add sufficient resistance that you create a local hot spot which is enough to melt the connector, even without blowing a fuse or overloading a wire.
Even at just 10A / 120W, if all dissipated into that corroded connector, will easily melt it.
Check along the wire - was it a local hot spot at the connector, or is the whole length of that wire melted?

You probably just got unlucky with a dirty connector, but could also be a lazy starter solenoid - connect it directly to the battery and use a current clamp to test how much its drawing. If you don't have one, then connect it via a fuse and see which one pops.

 

[Engineer8000]

True that, especially in one of the main power supply circuits.

 

[76 FJEID]

Some corrosion built up in the connector can add sufficient resistance that you create a local hot spot which is enough to melt the connector, even without blowing a fuse or overloading a wire.
Even at just 10A / 120W, if all dissipated into that corroded connector, will easily melt it.
Check along the wire - was it a local hot spot at the connector, or is the whole length of that wire melted?

You probably just got unlucky with a dirty connector, but could also be a lazy starter solenoid - connect it directly to the battery and use a current clamp to test how much its drawing. If you don't have one, then connect it via a fuse and see which one pops.

Good stuff. Hoping like you said a corroded connector. I have a new connector on the way and will inspect the wire all the way back. Thanks for your insight. New to the FJ.