the fuel filter filters out fuel from the fuel tank then to the carburetor or your manifold which ever you have so that when it gets combusted it won't have sediment from the fuel tank so if it's got problems you won't get fuel or it will (starve) your engine for fuel making it kinda sluggish or not run smooth. hope this helps and is what you were looking for if you need any other automotive questions just ask i'm going to school for this stuff.
