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How to Bleed a Fuel Line

By Edited May 9, 2016 0 1

Every summer is the same, when the weather gets warm we go outside more to work and play. The tools we use are powered by gasoline and diesel engines that need to be restored to good working order before we can enjoy them or they will be damaged by our lack of care. Being stored for winter involves draining all the fuel and preparing the engine for storage. Restart the engine by refilling and bleeding the fuel lines to expel trapped air that can stop an engine from running, or even starting properly.

Things You Will Need


Crescent wrench

Full tank of fuel


Step 1

Open the fuel tank and fill with approved fuel until the tank is full or until fuel reaches the inlet tube of the tank. Diesel and gasoline tanks can vary in the procedure to bleed a fuel line but a full tank of gasoline or diesel is required. Diesel engines rely on gravity to keep some pressure in the lines that require a tank to be full you bleed a fuel line.

Step 2

Remove the air cleaner from the top of a gasoline fueled engine. After having run out of gas, or been in storage for over sixty days, the way to refill the fuel line is with the electronic ignition. Operating the gasoline fuel pump, the engine must have a working battery and good charge to turn the engine over when asked to bleed the fuel lines.

Step 3

Locate the diesel fuel filter. Open the bleeder valve located here. Use the primer pump or activate the fuel pump to push air of a diesel fuel line. Diesel tractors and engines are more prone to having trapped air in the fuel lines that feed the injectors. Different than a carbureted gasoline engine, a diesel motor can perpetuate a problem that results in poor performance by not allowing air to fully escape the line. Tighten the diesel fuel filter bleed valve and move into the engine bay.

Step 4

The carbureted gasoline engine can quickly bleed its own fuel lines simply by attempting to start the engine without allowing it air to start. The best way to accomplish this is to completely cover the opening into the carburetor with your hand. Turn the ignition key to the start position and hold for three seconds. The hand that covers the carburetor will eventually become wet with fuel that the fuel pump is sending into the carburetor. Attempt to start the engine three times, that's a total of nine seconds of fuel delivery. If the engine becomes flooded with fuel making it unable to start after this procedure, wait 20 minutes before attempting to start again. This will bleed a gasoline fuel line.

Step 5

Diesel engines that need the fuel lines that feed the injectors bled of air will need to disconnect each injector fuel line and then prime the fuel system until fuel is coming out of each injector line the same. Reconnect the injector lines and restart the engine. This process will bleed a diesel fuel line.

Bleeding a Fuel Line is all about getting the air out of the lines. Keep valves and fuel lines free from extra air entering the lines by always maintaining the ends of hoses and bleeder valves at all times.

Tips & Warnings

TIPS: A rag to capture extra fuel will prevent you from possible fire and keep a gasoline engine from flooding. Put a rag inside the carburetor when bleeding a gasoline fuel line to soak up much of the fuel that would otherwise flood a gas engine.

WARNING: If you bleed a fuel line on a hot engine you risk an explosion and fire, possible burning yourself, your assistant, and the house you live. See how silly that sounds? Protect yourself from fire by working only on a cold engine and having the proper fire extinguishers available in the work area.


Sep 10, 2009 9:11pm
Great article on how to bleed a fuel line I had no idea.
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