Filters serve a vital function in engine fuel systems .Unfiltered fuel may contain several kinds of contamination like dirt ,rust, etc….If these substances are not removed before the fuel enters the system,that will cause rapid wear and failure of the fuel pump and indectors.Fuel filters need to be Replaced at regular intervals.If a filter is not replaced regularly it may become clogged with contaminants and cause a restriction in fuel flow ,causing an appreciable drop in engine performance as the engine struggles to draw enough fuel to continue running normally.