What does an aluminum filler neck do? The fuel filler neck is a piece that connects with the fuel tank and the gas cap. It can be a metal hose connected to the fuel tank or a rubber hose that functions with hose clamps to help hold the neck of the gas tank. We can get lightweight steel, aluminum, or chrome plating for the metal neck. In today's time, we might get more powder-coated fuel tank filler necks as after the coating; it becomes lifelong. The best qualities of fuel filler caps are long-lasting, but we also need to remember that corrosive chemicals can make them wear and rust over time. People often experience holes and cracks in the filler caps that allow the fuel to leak out. Such things can create a fire hazard, allowing dust and debris to seep inside. Over time we can see the performance of a vehicle deteriorating. Other reasons for defective filler neck include accidents or collisions, but those all can be temporarily patched up with an adhesive.