Fuel Filter Replacement

Dane from the Heights Four Seasons MasterLube demonstrates a typical fuel filter replacement procedure.

sample-fuelfilterDescription: The typical fuel filter for most fuel-injected cars consists of a high-pressure canister filled with filtering media. Filters may have clamped, threaded or special fittings to ensure reliable connection to the fuel system. Filters for carbureted engines may be located at the inlet of the carburetor or inline. Filters for carbureted engines do not need to withstand the same pressures as those for fuel-injected engines.

Purpose: Fuel filters trap harmful contaminants that may cause problems with carburetors and intricate fuel injectors. Fuel filters for carbureted engines only clean the fuel before it enters the float bowl. Injection filters, on the other hand, clean the fuel whenever the fuel pump runs (unless the fuel injection system is a returnless design). Fuel moves continuously up the supply side, through the filter to the fuel rail or throttle body. The fuel that doesn’t make it into the engine returns to the tank and the whole process starts over again. With a full tank of gas, the filter may clean the volume of fuel in the tank many times before it’s all used.

Maintenance Tips/Suggestions: On carbureted cars, replace the filter once a year. On cars with fuel injection, some carmakers don’t recommend replacing the filter at all during the first 100,000 miles of “normal” driving. Since normal usually constitutes severe driving because of less than normal conditions, it’s best to replace the filter every year or 15,000 miles. A contaminated filter can restrict fuel flow from your car’s electric fuel pump, eventually taking a toll on its life. Frequent filter replacements remove all doubt about whether the filter may cause other problems down the road. Most filters on domestic cars and trucks hide underneath on the frame or body. Just the opposite is true on the imports. They usually put their filters somewhere in the engine compartment. If you decide to change the filter yourself, be careful. Fuel injection systems maintain pressure in the lines that must be relieved prior to filter replacement. Don’t forget that gasoline is extremely flammable. Procedures vary for relieving pressure. Also, some filters require special tools to replace the fuel filter. Because of these technicalities and because of most filter locations, it’s best to have your car’s fuel filter replaced by a qualified service professional.