Trying to figure out how filter works. I have a fuel filter/water seperator? It is one or both, its inline with fuel line. It has what look like a washer and nut on bottom. The whole round piece does not screw off like normal filters. If I loosen the nut gas leaks out. Do I pull it apart and clean it or what. I dont like pulling something apart until I know how it works. Any help would be great.