Fuel Line Check Valve

check valve
A valve that closes to prevent backward flow of liquid
Limits the flow of gas to one direction only. Use a check valve between the bubbler and generator to prevent unwanted pressure build up in the generator, and a safety against a low level bubbler. A check valve, such as used on torches, is recommended.
A mechanical device in a pipe that permits the flow of water or air in one direction only.
A check valve, clack valve, non-return valve or one-way valve is a mechanical device, a valve, which normally allows fluid (liquid or gas) to flow through it in only one direction.

fuel line
a pipe that carries gasoline from a tank to a gasoline engine; "the car wouldn't start because dirt clogged the gas line"
The metal, plastic, or rubber hose or pipe through which the fuel passes from the Fuel tank to the Fuel pump to the Carburetor or Fuel injector nozzle.
A fuel line is a hose used to bring fuel from one point in a vehicle to another. It is commonly made of reinforced rubber to prevent splitting and kinking.