This Architectural Drawing is AutoCAD 2d drawing of Fuel Filler cap details in AutoCAD, dwg file. The FUEL FILLER CAP serves as a lid for the fuel tank of motorcycles and has a valve function for regulating the pressure in the tank. Filler Caps and Fuel Caps Information. Filler caps and fuel caps seal filling ports in tanks and reservoirs holding liquids or granular media. They prevent the ingress of foreign materials into and the leakage of fuel or media from the reservoir. For more details and information download the drawing file.