With Bendix Electronics

Fuel Pump:

PURPOSE AND LOCATION
The electric fuel pump, located in the gas tank, supplies the fuel system (and injectors) with the fuel pressure/amount needed to operate the injection system.
Operation of the pump is controlled by the fuel pump relay (part of [1][2]system relay), which is energized by the fuel injection control unit. The relay will only be energized during cranking (starting) or while the engine is running. This will keep the fuel pump from running when the engine has stalled in an accident or similar incident. The control unit uses the engine speed signal as an input for fuel pump control.

Fuel Pump (Typical):

CONSTRUCTION
The electric motor actually operates in the fuel in the fuel pump housing. This is possible, because the housing never contains an ignitable mixture. The fuel is used as a lubricant and coolant for the pump motor.
A check valve is incorporated in the fuel outlet and a pressure limiter valve is located on the pressure side of the fuel pump housing with a return passage to the fuel inlet side.

Roller Pump (Located In Fuel Pump):

The pump components consist of the following:
The pump is of the roller-cell type. The pump chamber itself is cylindrical, in which an eccentrically fitted pump rotor disc rotates. This is fitted with metal rollers which are held in pocket-shaped recesses around the circumference.
In order to maintain a constant pressure in the fuel system under all possible operating conditions, the pump supplies substantially more fuel than the engine would ever need at any engine load.

OPERATION
When the rotor disc rotates, the rollers are pressed outwards by centrifugal force and act as a circulating seal. A pumping action is created by the circulating rollers which draw in fuel at the inlet port and force the fuel through the outlet port into the fuel system.
When the pump is shut off, the check valve in the fuel outlet will close, therefore prohibiting the fuel from returning to the fuel tank via the fuel pump. The check valve will therefore maintain a pressure in the fuel lines called the "rest pressure".
The maximum fuel pump pressure (not fuel system pressure) is dependent on the calibration of the pressure limiter. If the fuel pump pressure exceeds a preset limit (for example a clogged fuel filter), the pressure limiter will open a by-pass to the fuel inlet side of the pump.


SPECIFICATIONS
For all fuel pump specifications see SPECIFICATIONS.