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My engine keeps dying. It's a brand new rebuild, the batteries and generator are good. I have to keep the throttle up to keep it running, and it sounds like it's running rough. When it dies, it can take up to 20 minutes to restart it. I live in Austin, TX, with a current temperature of about 85. The fuel line goes between the engine block and exhaust manifold. Do you think it's vapor lock?

I have noticed, if I spray thrust quick starter fluid in there, it starts up

I'D GO EASY ON THE STARTER FLUID DEADGUY.. I BURNED VALVES
ON A FLATHEAD HARLEY MOTOR ONCE (AT LEAST I BLAME IT ON
THE STARTER FLUID CUZ I USED IT REGULARLY)

Check for a vacuum leak. All lines, carb base gasket, and adjust your valves. Lots of threads on rough running non idleing engines here and Willysmilitaryjeeps.com. Read them all and the results. You will get the idea. John

First thing to do is insure you have fuel all the way to the carb. The easiest first check to make is let her cool off and then remove the gas cap from the tank and start her up. If she runs with no more feed problems then you have a blocked vent system from the top of the tank to the air cleaner if you have an Early M38A1 with fording system plumbing or the vent valve on the tank is stuck closed. Are you currently running a vented or unvented gas cap? The unvented cap will have "pressurized remove slowly" on it

If she quits again then disconnect fuel line at carb and when the engine cools and you have a tight fitting hose over the end of the fuel supply line and the other end of the hose in a plastic container out of the engine compartment start her again. You should get about 4 oz's of gas in the container in 3 or 4 seconds. If you do place the end of the hose under the top of the gas and see if you are getting any air bubbles along with the gas.

No gas means check for plugged plumbing between the end of the line and the gas tank.

Bubbles means you have a very small air leak into the plumbing usually caused by a very slightly loose fitting or corrosion pit holes in the feed tube in the tank.

If no gas, no plugged lines and no bubbles connect a pressure gage to the pump and look for about 4 to 5.5 pounds at 1800 RPM.

Try to completely troubleshoot the fuel system before jumping to the induction system and then the ignition system. It's often hard to be patient and not shot gun troubleshoot but the results of avoiding a shot gun approach are usually a quicker and more accurate diagnosis of your problem.