Yet another CUCV not starting thread

[Postal0311]

I have a 86 M1008 which is my daily driver. About once a quarter it surprises me with a new problem. Last quarter was a leaking heater core, today it wouldn't start.

Or, more accurately it started right up, ran for 1 second, stopped, and wouldn't start again.
Smoke was observed leaving the hood, upon opening the hood the smoke was around the area of the batteries, but I was unable to locate the source of the smoke.


Batteries are 2 years old, they were pulled and tested good.
Previous owner installed a second battery gauge. That shows the batteries putting out 12 v.
Headlights & fan still work.
Stock battery gauge is showing 0.
Glow plugs have been bypassed with a manual push button. The push button is currently doing nothing.
Starter relay had previously failed, Doghead modification done. When the key is turned the new relay is heard to loudly click(as per usual).
When the key is turned, the starter clicks, but the starter doesn't crank when key is turned to start.
Battery terminals are clean and in good shape.
I've been cleaning ground terminals. They don't appear to be the issue.
I've been checking the continuity of the wires to the batteries, and the glow plug solenoid, and they all appear to be good.

So at the moment I am stumped.
One of my first thoughts was that the starter died, but I don't think that would cause the original battery gauge and manual glow plug button to stop working.
I'm unsure of what caused the smoke. I have not found any damaged wiring.
I've started checking fusible links, but I'm not familiar with all their locations, so I don't think I've checked all of them yet.

The batteries are still under warranty, so I will probably take them to another shop and have them tested again.

Any suggestions?

 

[cucvrus]

Burned out fusible link on the right side behind the rear battery. Check all the wires under the buss bar. Something made the smoke and I am guessing it was there. It may still have the insulation and the wire is just burnt off inside. Everything needs checked. is the cable loose on the battery and the starter. Loose cable on starter can make smoke. Report back.

 

[Abbylind]

Ditto theres a fire somewhere under that hood..

 

[Rustyshackelford]

Short at the starter relay can also cause this smoke. If the dog head modification was done the nuts on top of that relay can easily be short circuited cause this problem

 

[Postal0311]

It may still have the insulation and the wire is just burnt off inside. . . Report back.

Thank you.

Slowly went back and checked the fusible links off the buss bar. Found a failed wire by pinching them. Replaced the fusible link with the same spec one(had to go to two auto parts places to find the right one.)

Replacing the fusible link caused the instrumentation to work, and allowed me to glow the plugs.
Attempting to start the truck instantly burned out the replacement fusible link.
I need more daylight so I can work on this more.

-edit-

Ok, looking at the wiring diagram I think it is the wires to alternator 2. I'll check for damage to the wires tomorrow.

 

[Postal0311]

Short at the starter relay can also cause this smoke. If the dog head modification was done the nuts on top of that relay can easily be short circuited cause this problem

Checked the relay, don't see any issues there.

Checked out Gen 2 with my multimeter. The isolated ground appears to still be good.
I'm thinking now that it is the starter. Had issues with this starter before so I went ahead and ordered a replacement.

 

[Rustyshackelford]

It's not the relay itself I'm talking about. It's the nut on top of the relay coming in contact with something. Check its vicinity for something that could come in contact with that nut.

 

[Postal0311]

Yes, understood.
I have the panel the relay is mounted on removed and sitting on the floor. Those terminals are covered in liquid electrical tape, and are most certainly not touching anything.
I'm fairly sure that isn't the issue. It may be the wiring too those terminals, but I'm not seeing anything that is clearly an issue. That said, I also don't really know what I'm looking for.

 

[Postal0311]

Replaced the starter over the weekend, that sorted out.

 

[cucvrus]

The starter was shorted out? Or that sorted out your problems?

 

[Postal0311]

Sorted out my problems.