Stranded Square

[Smitch320]

I wonder if it could be the wiring harness going bad.

 

[HotRodPC]

BAD WORD. It has happened again.

Did you mean ****, It has happened again? What happened again?

 

[chengny]

BAD WORD. It has happened again.

And, unfortunately, it will most likely continue to happen - until you find the problem that is causing the fusible link to blow. And that problem will almost certainly be an intermittent short circuit to ground.

Assuming that the short to ground in the wiring is somewhere in the engine compartment, there is only about 6 feet of wire to inspect.

See if you can follow the wiring diagrams below. They show the 2 main branches coming off the battery. Both are protected by fusible links. The branch that supplies the lighting and horn circuits is functional. Everything else is not working and they all pass through the ignition switch. Because you have changed the ignition switch it can pretty much be ruled out as the issue.

 

[HotRodPC]

Ahhh OK. The fusible link blowing. I'd first suspect the starter wires grounding out on the exhaust. You should have the heavy battery cable wire, like a 10ga red wire which is where the Fusible link is inline with to the fusebox IIRC, and then a purple starter activation wire. I'd be checking at the starter and go from there if it were me.

 

[Smitch320]

Little bit of an update. Haven't had time to fool with my truck lately,

Ok, so I have ruled out the issue with the fusible link to the starter. Occasionally it wil start, choke light is on, ignition buzzing etc. it will run then it will cut off out of nowhere- then I lose power besides lights and horn. Giving me the original symptoms I had.

Is this something shorting out possibly? Bad ground some where that I am bypassing on accident. I have followed that wiring diagram and can't find anything obvious.

Like always,

Thanks for the help.

 

[robert8096]

Occasionally it wil start, choke light is on, ignition buzzing etc. it will run then it will cut off out of nowhere- then I lose power besides lights and horn.
Thanks for the help.

Check for a loose wire or bad connection where the under hood wires connect to the back of the fuse box. I had this problem with my 74 and it was a bad connection where the under hood wiring harness connects to the fuse box.

The tuck would be sitting there running great and all of a sudden die and not even engage the starter. Wiggled the wires at that junction and she would fire right back up like nothing ever happened.

Good luck

 

[chengny]

I just checked my work - I traced the wiring diagram incorrectly.

The power to the ignition switch (which is assumed to be the problem wires) goes through a fusible link near the starter, up to the junction block on the firewall, another fusible link about 6 inches from the JB and then through the firewall.

Check for a good steady 12VDC at the terminal screw on the junction block. Make sure the nut that secures the ring terminals to the JB is tight. Be careful when you tighten it - that screw often breaks free from the back of the JB.


Generally speaking, fusible links do not fail intermittently - they are either always good or completely blown. It is probably a broken wire or loose connector. I would take my meter, and starting at the JB, just check for voltage as you go down the line towards the ignition switch.