Hot truck won't start

[militarypotts]

On July 4th I did two parades. The outside temperature was 102 degrees! When I got to the second parade and shut my truck down, it would not start. Let it cool down for 45 minutes and it restarted with no problem. Last night was over 100 degrees, again I drove the truck to a cruise night about 7 miles from my house and it would not restart when I got there. Let it cool down for a couple of hours and it refired immediately. Could this be vapor lock, or just the outside temperatures playing havoc with my truck? I never, ever have problems starting my truck. Not blaming the truck at all, it's the weather that really seems to be the problem. Letting the truck rest today, as it's about 100 degrees outside again. Global warming???

[Pineyguy]

I'd vote vapor lock. Its happened to me before. You can re-route the fuel line away from the side of the oil pan. I was planning on doing it but now I have a 6.2 sitting in the garage waiting.

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[ou719]

elctric fuel pump, I know its not stock but itll help.

[Don Cavey]

What coil does it have? Is it the chrome plated one or an original "military" coil. I had the same problem. I am not exactly sure but I got a used coil for a lot of money and have not had the same problem. I even tossed the chrome (China) coil into the bucket.

I have a NOS ignitor for the truck but have not "Gotten A Round Tuitt" yet. I don't remember vapor lock ever being a problem with the truck that I drove in the desert of Utah in 1969. But the truck was only two years old. That is not to say that it isn't vapor lock. I have experienced that one time in the Corvair...

My bet would go for the coil. Just a thought.

[white433]

Coil no doubt about it.

[militarypotts]

Never thought about the coil to tell you the truth. My guage read in the green on both occasions. I was actually wondering if it could have been an overheated starter motor? In the end, all it took was a little time for the truck to cool down, and it fired right up.

[Don Cavey]

Never thought about the coil to tell you the truth. My guage read in the green on both occasions. I was actually wondering if it could have been an overheated starter motor? In the end, all it took was a little time for the truck to cool down, and it fired right up.

Now I am confused. Did it turn over and not start or did it not turn over when you tried to get it going? If it didn't turn over, then it could be the starter or circuit associated with that (foot switch if original). But if it just spins and doesn't start running then sounds like ignition issues like the coil. Please let us know.

[moose3d]

Had the similiar problem last year in the parades in my neck of the woods with my M725, run fine in the parade and then would flood, let it cool down/let plugs dry and ran fine, it was overloading the cylinders with fuel at those low speeds. At 55 MPH it was purring like a kitten, so I rebuilt the carb and problem solved, now it cruises at 60 MPH and purrs even better. Just a thought if it's not the coil.

[militarypotts]

After shutting the truck down and trying to start it again, it cranked for about 3 or 4 seconds and started to slow down, so I stopped at that point and let it cool down. So what I'm saying is that the truck did crank, but labored. Power to starter and floor switch was flowing, just couldn't turn over the engine more than a few times. I'm quite sure it was heat related. Had truck out last night in much cooler temps, and it operated perfectly. I'm figuring if it was vapor lock, the truck would crank and crank and just not start. This wasn't the case. In the nut shell, it was having trouble cranking at proper starter speed. Hope this clears up what I was trying to convey. Lot's of hot rods at the shows were having problems with the heat. In fact, alot of guys refused to even drive their cars in the 102/103 degree temperatures for fear of vapor lock or heat related issues. Not blaming the truck at all, just need to be alittle more careful in extreme heat conditions.

[Don Cavey]

Thanks for the clarification. I think that either the starter has shorted turns in the armature or is rubbing inside due to worn bushings. Could also be worn brushes. You may want to find another starter and see what happens. Also, monitoring the voltage to the starter when cranking should help to identify the problem. You could even try pouring cool water on the starter and see if that helps. With 24 volts, the windings are a lot smaller and that starter should just fly unless the batteries are old/weak. Believe it or not, more batteries fail in hot weather than the winter. Maybe another member has an extra starter that he/she would give up?