In years past, a mechanical fuel pump and carburetor were used. In order for engines to run better and produce less harmful emissions, electronic fuel injection systems have taken their place. On modern vehicles, fuel is supplied by an electric pump and metered to the cylinders by computer controlled fuel injectors. Fuel Tank The fuel tank stores the fuel. Inside the tank, there is a float that signals the computer systems and/or fuel gauge as to how much fuel is in the tank. On newer vehicles, the fuel pump, fuel, filter, and fuel pressure regulator may also be housed inside the fuel tank. Fuel Injector The fuel injector is a nozzle-and-valve assembly that sprays a precise amount of fuel from the pressurized fuel system into the engine to aid in the combustion process. Additional Key Component — Fuel Pump The fuel pump draws fuel from the fuel tank and sends it to the engine.