Fuel Pump: Description

There are two basic types of fuel pumps. Most carburetted vehicles use an engine-mounted mechanical pump. General Motors diesel models use either a mechanical or an electric pump. Gasoline vehicles with fuel injection use an electric pump, normally located in or near the fuel tank.

Some models use a low pressure and a high pressure electric pump. Generally, one pump will be located in the fuel tank, and the other externally. This provides adequate fuel delivery during extreme vehicle maneuvers and on steep inclines when the fuel tank is near empty.

Vehicle manufacturers recommend that the pump be replaced as an assembly if found defective. Test pump for pressure, volume, and vacuum (suction). Some pumps will have an extra connection for fuel and vapor return to aid in hot starting and to prevent vapor lock.