Erratic spark

31love

New member
Drove the 31 today but when I got home it wouldn't start. Cranked and cranked...no luck. Pulled coil wire and found I only had spark when I first hit the starter button and at the moment I let off the starter button. Got to looking around. One of the leads in the terminal box looks like it melted the plastic back of the terminal box. Terminal box got hot due to excessive cranking, I would guess???? The wires in the terminal box sure don't look like they are in the best shape. Would this cause the bizarre spark issue or would it just be a symptom of another issue?
 
The terminal box should not be getting hot, it has nothing to do with the starter. If it is hot and melting it has a problem and needs to be fixed before it gets worse.
 
Starter current does not pass through the terminal box.
Original terminal boxes are bakelite (phenolic thermoset) and do not melt, you must have an aftermarket box. Those are known for shorting through the backside to the firewall.

I would remove the terminal box from the firewall and replace it. Make sure the screws of the replacement are not exposed on the backside to the firewall. Some people fill in the recess with the exposed screws on the back of aftermarket boxes with epoxy, like JB, or place an insulating sheet behind it. Check security of all the connections behind the dash panel and at the coil while you're at it.
 
Sounds as if the terminal box connections are loose or corroded. Also as '30 mentioned there have been some instances of the bolts contacting the fuel tank and grounding.
 
Mike K hit the nail on the head on post #4. I would figure on replacing both wiring harnesses and the terminal box. If you cant find a good used original terminal box, I would be sure and fill the recess behind the terminal box screws with two part epoxy.
 
Drove the 31 today but when I got home it wouldn't start. Cranked and cranked...no luck. Pulled coil wire and found I only had spark when I first hit the starter button and at the moment I let off the starter button. Got to looking around. One of the leads in the terminal box looks like it melted the plastic back of the terminal box. Terminal box got hot due to excessive cranking, I would guess???? The wires in the terminal box sure don't look like they are in the best shape. Would this cause the bizarre spark issue or would it just be a symptom of another issue?

I would check the amp meter to make sure the wires aren't loose or shorting. The wire nuts on the back of the meter are known to get loose and/or short to ground.
 
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