How to Bleed Air in a Gas Line

by Jonathan Pfeiffer

Vehicles and tools powered by gas that have been stored for awhile must have their fuel lines bled so any air is removed before being used again. Fuel lines containing air can cause the engine to not run properly. Generally, air is introduced to the fuel lines when there is a leak or during fuel draining for equipment storage. Very little mechanical knowledge is required when bleeding fuel lines.

How to Bleed a Gasoline Line

1

Fill up the gas tank with fuel.

2

Start the engine but do not allow air into the system. Have a friend turn the key in the ignition to “Start” for approximately 3 seconds. While your friend “starts” the engine, place one hand on top of the carburetor air intake. At this point your hand should get wet from the fuel. Repeat this step three times.

3

Allocate approximately 20 minutes for the engine to sit if flooding occurs while bleeding the fuel lines. Repeat the process if needed until the fuel lines are completely free of air.

How to Bleed a Diesel Line

1

Fill the fuel tank with gasoline to cause pressure to build within the fuel lines.

2

Locate the fuel filter. The filter can be found by tracing the fuel lines back to where they reach the engine filter. In cases where a fuel injection pump is involved, follow the fuel lines until you arrive at the pump. A majority of diesel fuel injectors and filters have a screw specifically designed to bleed the fuel lines. Utilize a screwdriver to loosen the screw.

3

Push on the mechanical lift pump lever. Continue to pump the lever until you see fuel coming out of the bleeding screw. The fuel will appear frothy at first. Once the bubbles subside, lock the bleeding screw back down. Use rags to soak up any fuel spills.

Warning

  • close Do not attempt to bleed the lines on a hot engine; doing so may result in a fire. Make sure the engine is cold when starting this process.

Items you will need

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