BOSCH Electric Fuel Pumps: Description

Bosch electric fuel pumps are roller cell pumps. They operate on 12 volts and supply fuel to injector units. Pump is of the positive displacement type and output pressure is limited to about 28 psi by a pressure regulator valve. Pumps with a return line have an internal pressure relief valve which opens at about 64 psi. Pumps without a fuel return line use an overflow valve which opens at approximately 73.5 psi. An eccentric rotor carries small rollers in pockets at its circumference, which seal the variable chamber volume against the internal walls of pump housing. Fuel pumping action is created by the rotor and roller movement.