'68 keeps dying

[pcdude91]

I have a '68 F-100. I am currently driving it around my yard only, as I have no tag for it. Lately, I will be able to drive it around for about 10 minutes, and it idles down. After about a minute of this, it won't start. If I let it sit for about 5-10 minutes, it runs fine. What's going on?

[Banjo]

Next time it does that, remove the air cleaner and using a flashlight peer down into the carb primaries and work the throttle by hand to see if you ran out of fuel. From the vague description, hard to tell what's happening. Does it backfire of just stop running? It could be your fuel lines are clogged up and not getting enough gas or fuel pump dying or choke slapping shut killing mixture (rich) or could be ignition coil. Could be fuel getting vaporized (vapor lock) from a fuel line too close to a heat source.

[jzjames]

sometimes when the engine gets warm, the carb will have a slight flooded condition when you shut off the motor. When you try again, after you shut it off, just turn the key without touching the gas pedal to see if it fires right up.

[pcdude91]

I think this condition has something to do with the heat. I tried to drive it yesterday, and it ran even shorter. Somebody told me there was a gasket or something like that under the carburetor or intake that would cause this, and it might have been damaged when I took off the carburetor to rebuild it.

[michael69]

Could also be bad coil they stop working when they get hot if its bad and will crank again when it cools off.

[fordman]

my first thougth was coil also. but since you said yo uhad the carb off. mayeb that gasket is leaking and causing a vacuum leak. but if it runs fine and just suddenly dies. i would say coil again. when this happens again check to see if you have spark and or fuel. then we can narrow it down for you.

[R.Smith]

My 71 did the same thing. Turns out the gas tank was full of fine rust from sitting for a few years empty. The rust was sucked into the fuel filter enough to restrict it but not totally block it. The truck would run for about 10 miles then quit. After sitting for a few minutes, it would start and run for a few more then quit.

To check it, unscrew the cannister filter on the pump and look at the filter. Mine was packed with sandy rust. Also, disconnect the fuel line before the pump and make sure gas is flowing from the tank. I've had that problem too.

[pcdude91]

My dad had an idea to test the gas tank theory. We put an old lawn mower gas tank under the hood, and hooked it up to the fuel pump. I drove it around, and it ran fine. It never quit, and never tried to. So there must be something in the fuel tank or the lines leading from it. I will check them as soon as possible. Thanks to everyone for your help.

[AK F100]

My dad had an idea to test the gas tank theory. We put an old lawn mower gas tank under the hood, and hooked it up to the fuel pump.

That's a pretty good idea right there.....

[4th effie n counting]

I used a 1 gallon gas can to find out same thing. I put a $3 plastic fuel filter on flex line under cab to catch rust before it got to pump. I carried a spare in glove box so when it got clogged i changed it on side of road. All this after i cleaned it out as best i could.
You can get tank boiled out at some radiator shops for around $30, I did this once and used tank liner from Eastwood Co. in my '60 f100.
You can also use marbles or nuts and shake the dickens out of it and repeat and repeat, until no more rust comes out.
If you have much gas in the tank I might suggest staring it, before it stalls, turn off ignition, remove flex line under cab and let gas run into gas cans, if you do it like this it is under pressure so no sucking of gas into your mouth. Trust me a half full tank is a booger to remove, especially by yourself.(my gauge didn't work I didn't realize how much was in my tank)

[mrtleavitt]

Yup same thing here. Bad gas tank sent rust and sludge through the system, clogged the filters and ruined the pump at the same time. Blew out the lines with a compressor, new tank, new filters, problem solved!