Fuel supply system

• E65, E66

The fuel supply system on the BMW 7-Series is requirement-orientated and thus depends on consumption.

The DME calculates the amount of fuel required on the basis of various operating variables.

In turn, the engine's current fuel requirement is calculated from this value. The DME requests this value as a volumetric flow with the unit "liters per hour".

The DME sends this request on the following path: DME (digital engine electronics -> PT-CAN -> SGM (safety and gateway module) -> byteflight  -> SBSR (B-pillar satellite, right) -> EKP (regulated fuel pump).

The B-pillar satellite, right converts the amount of fuel requested into a nominal speed for the fuel pump.

The pump speed is regulated via the cycle ratio of a pulse-width-modulated signal. This rectangular signal gives the effective supply voltage for the fuel pump: The longer the pause between the edges of the rectangular signal, the lower the supply voltage for the fuel pump. The fuel pump delivery volume is correspondingly lower. The fuel pump speed is sent back to the B-pillar satellite, right as an input variable.

This method has the following benefits compared to the conventional way of actuating the fuel pump (fuel-pump relay):

• Lower current draw from fuel pump
• Reduced heating up of fuel
• Longer service life for fuel pump
• No fuel-pump relay needed

The flow of fuel is interrupted in the event of a crash of sufficient impact. This prevents the fuel from escaping or igniting (emergency fuel cutoff).

The fuel pump can be reactivated by switching the ignition off and on again.

If the request signal from the DME or the pulse-width-modulated signal from the SBSR is not received: The fuel pump will operate a maximum delivery capacity. This guarantees sufficient fuel supply for all operating conditions (emergency operation).

• E60, E61, E63, E64 and E70

The DME switches the fuel pump on using the fuel-pump relay.