Fuel pump — design description (BMW X5 E53)

The fuel pump is a rotary, submersible type with an electric drive, manufactured by Bosch (Germany), and is installed in the right half of the fuel tank. The fuel supply pressure at a voltage of 12 V at the terminals of the battery is 4.0 kgf/cm².

The fuel pump rotor is mounted eccentrically on the shaft of the electric motor with permanent magnets. In the chambers located around the circumference of the rotor, there are metal rollers that are pressed against the surface of the pump housing under the action of centrifugal forces, providing a reliable seal. Fuel sucked into the gaps between the rollers and the pump housing is fed into the discharge pipe. The installed check valve closes the fuel supply channel. As soon as the fuel pressure exceeds 4.0 bar (kgf/cm²), the ball of the safety valve closes the fuel supply from the tank.

To maintain the required fuel pressure in the fuel system, the fuel pump supplies a quantity of fuel exceeding its consumption by the engine. Thus, at full load, about 70% of the injected fuel drains into the tank after passing the pressure regulator. The fuel pressure regulator of the fuel injection system is set to 3.5 bar (kgf/cm²). The working pressure of the suction jet pump is 1.0-1.3 bar (kgf/cm²).

The pump capacity at a voltage of 12 V at the battery terminals is 2.06 l/min. The current consumption at a voltage of 12 V at the battery terminals is no more than 9.5 A.