by Thomas West
Modern cars and trucks use a fuel injection system to deliver the correct mixture of air and fuel to burn into the engine’s cylinders. The fuel injection system operates at high pressure; therefore, before performing any maintenance work on the fuel system, such as replacing the fuel filter, the fuel system must be depressurized. Depressurizing the fuel system will prevent a dangerous amount of fuel from splashing on it when you remove the fuel filter.
Loosen the fuel filler cap on the outside of your vehicle without removing it. Listen for the audible hiss to subside, indicating that pressure has been released in the fuel tank.
Locate the fuel lines that connect to your fuel filter. Note that on some vehicles the fuel filter is mounted under the vehicle on a frame rail, while on other vehicles the filter is located in the engine compartment. Check your owner’s manual for the location of your fuel filter. Loosen the fuel line fittings on the filter by turning them with a flare wrench counterclockwise, but do not remove the fittings completely.
Wait several minutes for the pressure in the lines to release. Be aware that fuel will escape from open fittings until pressure is released. Clean up any spills with rags.
Remove the fuel lines from the fuel filter if you are changing the filter; otherwise, leave them loose until maintenance work is completed. Tighten the fuel lines clockwise after maintenance work is complete and you want to re-pressurize the fuel system.
Tighten the fuel filler cap.
- If you do not want to loosen the fuel lines to relieve pressure in your fuel system, use the following procedure: Start the vehicle and let it idle. Locate the fuel pump relay fuse in your vehicle’s fuse box. Your vehicle’s fuse box may be located under the dash on the driver’s side or it may be under the hood. See the guide on the inside of the fuse box cover to find the proper fuse. Use a fuse puller and remove the fuse from the fuel pump relay. When the vehicle sputters and stops on its own, turn off the ignition. After all maintenance work is completed, replace the fuel pump relay fuse in its place in the fuse box. Turn on the ignition key and wait a few seconds for the fuel system to pressurize before starting the vehicle.
Things you will need
- Do not use a fuel filter designed for a carbureted vehicle in a vehicle that has fuel injection. The much higher operating pressure of the fuel injection system could burst a fuel filter designed for a vehicle that uses a carburetor.