Electric Fuel Pump - ISO/TS 16949

Electric fuel pumps generate positive electrical pressure in fuel lines, which drives fuel to the internal combustion engine. An ignition switch activates a relay that manages the higher current necessary to increase fuel pressure. Two types of fuel pumps are used in automobiles; mechanical and electric. All fuel injected cars today use electric fuel pumps, while most carbureted cars use mechanical fuel pumps. Mechanical fuel pumps are diaphragm pumps, mounted on the engine and operated by an eccentric cam usually on the camshaft. A rocker arm attached to the eccentric moves up and down flexing the diaphragm and pumping the fuel to the engine. Because electric pumps do not depend on an eccentric for operation, they can be located anywhere on the vehicle. In fact they work best when located near the fuel tank. ​Many cars today, locate the fuel pump inside the fuel tank. While mechanical pumps operate on pressures of 4-6 psi (pounds per square inch), electric pumps can operate on pressures of 30-40 psi. Current is supplied to the pump immediately when the key is turned. This allows for constant pressure on the system for immediate starting. Electric fuel pumps can be either low pressure or high pressure. These pumps look identical, so be careful when replacing a fuel pump that the proper one is used. Fuel pumps are rated by pressure and volume.