Fuel pump

On engines that use a carburetor (e.g. in older cars, lawnmowers and power tools), a mechanical fuel pump is typically used in order to transfer fuel from the fuel tank into the carburetor. These fuel pumps operate at a relatively low fuel pressure of . The two most widely used types of mechanical pumps are diaphragm pumps and plunger pumps. == High-pressure mechanical pumps ==

Pumps for modern direct-injection engines operate at a much higher pressure, up to and have configurations such as common rail radial piston, common rail two piston radial, inline, port and helix, and metering unit. Injection pumps are fuel lubricated which prevents oil from contaminating the fuel. Port and Helix pumps Port and Helix pumps are most commonly used in marine diesel engines because of their simplicity, reliability, and its ability to be scaled up in proportion to the engine size. These pumps usually run at a fuel pressure of . == Electric pumps ==

In fuel-injected petrol engines, an electric fuel pump is typically located inside the fuel tank. For older port injection and throttle-body injection systems, this "in-tank" fuel pump transports the fuel from the fuel tank to the engine, as well as pressurising the fuel to typically . While for direct-injection systems, the in-tank fuel pump transports the fuel to the engine, where a separate fuel pump pressurises the fuel (to a much higher pressure). Since the electric pump does not require mechanical power from the engine, it is feasible to locate the pump anywhere between the engine and the fuel tank. The reasons that the fuel pump is typically located in the fuel tank are: • By submerging the pump in fuel at the bottom of the tank, the pump is cooled by the surrounding fuel • Liquid fuel by itself (i.e. without oxygen present) isn't flammable, therefore surrounding the fuel pump by fuel reduces the risk of fire In-tank fuel pumps are often part of an assembly consisting of the fuel pump, fuel strainer and fuel level sensor (the latter used for the fuel gauge). ==Turbopumps==

Rocket engines use a turbopump to supply the fuel and oxidizer into the combustion chamber. ==See also==