No crank

[Rockerdog]

Had the oddest thing happen the other day. Went to pick up my dog at the vet and started the truck. It started fine. Cranked fast and started up. Drove it to the vet and it died in the parking lot when I hit the brake.
I tried restarting but it would not crank over. Headlights were dim as if the battery was dead.
I noticed that if I turned on the head lights, pushed the brake pedal or turned on the key, the ammeter would peg hard to the negative.
It was late and I had an injured dog in the truck so I used my AAA and called for a tow. When the driver got there we tried jumping it and it fired right up.
When I got home (very short trip about 3 minutes) I tried starting it again about 10 times and it cranked fine every time. Head lights were back to normal and so was the ammeter gauge.
I'm about to tear in to it but wondered if anyone had had the same problem?

Oh it's a 69 F250 CS 390 C6

Thanks!

[fordman]

bad alternator or regulator. the battery used up all its power. and since there was nothing to recharge the battery hittign the brakes use the last of the power so there was no power to go to the coil anymore.

[Rockerdog]

I'm just being lazy today LOL I hope it's as simple as a dead battery but it seemed more like a temporary short. The ammeter didn't just fall over to the negative it slammed over like something was grounding out and the battery started by itself after only 3 minutes of run time. Still it is an older battery. I'll test it at work Monday. If I find anything weird I'll post it here with pics

[Thunderfoot]

Check your ground cable from the battery to the engine for condition and good connections at each end.

[basketcase0302]

I noticed that if I turned on the head lights, pushed the brake pedal or turned on the key, the ammeter would peg hard to the negative.

I'd also look at your brake light switch. They do fail quite a bit, and there's a lot of metal down there for the terminals on the switch to short out on.

[fordman]

i would think that maybe the alt wiring or start relay wiring may have go thot and melted possibly.

[Rockerdog]

Thanks, basketcase, fordman and thunderfoot, you are ALL right!
I looked at the brake light switch and found a mess of taped up wiring.
When I removed the tape, I found the brake light wiring was fried!


Then I checked the starter solenoid and found the "Ignition" wire had also started to melt!


The battery is old but it seems to be working. Here's a shot of the voltage readings with the head lights on and then 1 minute after turning them off.


I DID find the battery cables in worse shape than I remembered. Guess it's time for some serious wiring repair!

[basketcase0302]

Glad you found it, I've seen more than one brake light switch short like that!
Voltage looks good.

[fordman]

i havent seen that until now.

[Rockerdog]

Well I finally found the real problem. Shelved the whole thing for a while due to various other commitments.
In spite of all the bad wiring pictured above, the actual problem, I think, was a missing ground screw between the distributor breaker plate and the main body of the distributor. The ground strap was shorting out.
I wont have another screw until tomorrow but that has to be it. If I disconnect the voltage regulator AND the distributor, the engine cranks over fine!

[Rockerdog]

Ok well I put the screw in the distributor ground strap and now it will at least crank over with the distributor connected but it still wont crank with the voltage regulator connected. At least I'm makin' progress LOL. Gonna check voltage at the regulator terminals next. Might be as simple as a bad regulator.

[Rockerdog]

Took the lid off the regulator and sanded the contacts. She started right away. When I shut her down it was back the the same old thing. Picking up a regulator tomorrow!