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Changing a Fuel Filter on Injected Engines

Changing Fuel Filters — Fuel Injected Engines

Protect the injectors in your electronic fuel injection (EFI) system by regularly changing your fuel filter. It is advisable for cars in normal commuter use to have their filters changed annually. Filters are necessary because gasoline is dirty. Impurities are the norm, not the exception.

First, be certain you have the correct replacement filter. Never try to adapt a carburetion-style filter for use in a fuel injection system. They are not interchangeable. Particularly with EFI, avoid any replacement that is labeled as a universal filter. Fuel filters designed for carbureted engines are not engineered for the high pressure that an EFI system generates.

Safety Concerns

Gasoline is highly flammable and its vapors are even more combustible, so proper ventilation and clean-up afterward are important. Some EFI systems have the filter mounted underneath the vehicle. If this is true for yours, be certain to have sturdy jack stands available for this job. You may want to consider wearing petroleum-resistant gloves. Allow the engine some time to cool before starting this procedure. Have shop towels handy for controlling and cleaning up spills. Be careful handling the old filter as it will contain some fuel.

Before starting, compare the new and old filters to be sure they are the same. You don’t need to have the old one off before realizing you got the wrong replacement part.

Fuel injection systems operate under considerable pressure, so care must be taken to relieve that pressure before the fuel line is loosened. Start by removing the fuse or relay that serves the fuel pump. Also, loosen the gas cap to relieve pressure in the tank. Start the engine and allow it to die from fuel starvation. Crank the engine for two or three more seconds to relieve any residual pressure. Do not forget to turn off the ignition key.

If your vehicle has its filter underneath, near the gas tank, put the rear end of the car up on secure jack stands.

Noting the filter’s orientation (which end is which), disconnect the fuel lines attached to each end. Some are equipped with quick-lock couplings that require a specific tool. Some are attached with “banjo fittings” and the replacement parts include two washers that you will also need to replace.

Remove and replace the old filter, remembering that it will contain some gas. Be certain the new filter is mounted correctly. They are engineered for gas to flow through them in only one direction. There should be an arrow on the filter to indicate which direction it should be. Tighten all fittings securely.

Re-install the fuse/relay and crank the engine until the system refills with fuel and the engine starts. At idle, examine the new installation for any leaks.

Updated on 12/16/2020

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