Problems restarting with warm engine on incline

[Oberfranke]

I have the following problem at outside temperatures above 86°F . I drive a longer distance. Then I turn the car off for about 30 minutes. After continuing to drive (I drive for 5-20 seconds) the engine cuts out. Usually slightly uphill on a small incline. The engine can be restarted with a lot of gas. But it is always a commotion and hinders the traffic. What can be the cause?

[ronn]

clog at the shut off valve........

[Big hammer]

The notorious vapor lock ?! When its hot outside and my A is hot, when restarting and she doesn’t fire right off I pull the choke for a couple of cranks and she fires, revving the engine and everything is back to normal !

[Will N]

I agree that it is probably vapor lock. While you are driving there is air moving through the engine compartment that keeps the fuel line and carburetor body cool enough to prevent the gasoline from boiling. When you stop the car the heat builds up and causes vapor bubbles in the fuel line because they've become too hot.



Some "cures" I've heard about for vapor lock (I don't know if any of these actually work): add Marvel Mystery Oil to the gasoline (it's supposed to raise the boiling point), insulate the gas line from the tank to the carburetor with aluminum foil, clip clothespins to the gas line (I can't begin to imagine how this can work) and finally, use ethanol-free gasoline.

[Marshall V. Daut]

Remove the gas cap and try to start the engine. If it keeps running, then the gas cap's air vent is clogged or missing. There is a distinct radiator and a distinct gas cap, the former not being vented. If someone installed a radiator cap on your gas tank (they will fit at either location), that interfers with the gravity flow of fuel to the carburetor because no air can get inside the tank to "push" the gasoline out. This would be especially possible on hot days.
Marshall

[Patrick L.]

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Vapor lock. Try installing a piece of light sheet aluminum [ trim coil] along the underside of the intake/exhaust manifold above the carb inlet to the exhaust clamp.

Also make sure the fuel cap is venting properly

[J Franklin]

Ethanol in gasoline increases your chances of vapor-lock.

[Dale'45]

Ober,
What I have found to cure this is shut off the gas valve and let the engine empty the carburetor. When you get ready to go again you have fresh, cooler gas in the carb and it restarts and runs without problems. Dale

[chap52]

Loosen the gas cap as Marshall said. Hope that's the issue. Chap

[Oberfranke]

Thank you very much, I got the following advice from a friend: add 5 percent diesel to the gasoline.

[Patrick L.]

Originally Posted by Oberfranke

Thank you very much, I got the following advice from a friend: add 5 percent diesel to the gasoline.

Yep, that'll help maybe. Or kerosene, same thing. I forgot about that.