How To Use Clothespins for Vapor Lock

by James McElroy
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Vapor lock happens when gasoline evaporates in an engine, usually in the fuel line, fuel pump or the carburetor. The fuel pump can not pump vapor, which decreases how much fuel reaches the engine and causes decreased power, rough engine operation or a complete failure of the engine. Clothes pins have been used for decades to help cure and prevent vapor lock in engines. However, there is debate about how clothes pins solve vapor lock -- some people think they act as a heat sink, drawing heat away from the fuel lines, or insulators which keep enough of the line cool to keep the gas liquid, and others say they create chambers in the fuel line that force the vapor back into gasoline.

Step 1

Turn off your engine and locate the metal tube running out of your carburetor and follow it the the fuel pump, which is mounted on the engine block. The pump will also have a flexible rubber-type hose coming out of it. This is the line that runs to the fuel tank.

Step 2

Place five clothespins on the metal line running from the carburetor to the fuel pump. These may act as heat sinks and draw heat out of the hose, or insulators which help keep the line from getting too hot.

Step 3

Clamp two clothes pins on the rubber fuel line that feeds gasoline to the fuel pump. Space them out on the line to create a chamber between them. This may help the vapor lock by creating a pressure chamber and turning the vapor back into fuel.

Step 4

Experiment with more or fewer clothes pins and by increasing or decreasing the number of clothes pins on the fuel lines. This is not an exact science, but an old-time, back-yard-type fix.

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