Though its exact position on each vehicle may vary, the fuel filter is generally located between the fuel pump and fuel tank. Its function is to remove impurities from gasoline being pulled into engine, keeping the fuel injectors clean.
Though delicate, fuel injectors have the important task of introducing gas to the engine's cylinders. Because the mixture of fuel and air that is used in the vehicle's combustion reaction must be precise, it is important that the fuel injectors be free of clogs. Thus, the fuel filter has the important task of keeping even the most minute sediment particles out of the stream of gas as it travels to the engine to keep the vehicle running properly.