Fuel-quantity control valve and high-pressure pump: Notes

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2017 BMW X3, 2016 BMW X3, 2015 BMW X3, 2014 BMW X3, and 2013 BMW X3. However, it is still accessible from the selected car via links, so may be relevant.

The fuel-quantity control valve is mounted on the high-pressure pump (CP4.2). The fuel-quantity control valve is controlled using a pulse-width-modulated signal. The DDE controls the fuel-quantity control valve at various pulse-duty factors while the fuel-quantity control system is active. The system adjust rail pressure to the specified level as calculated by the DDE.

The fuel-quantity control valve regulates the fuel flow from the low-pressure side to the high-pressure side of the high-pressure pump. This is how the desired fuel-rail pressure is achieved. Progressive reductions in the amount of fuel that the fuel-quantity control valve allows to flow to the high-pressure side produce corresponding reductions in the level to which the high-pressure pump charges the cylinders. The consequence is that less rail pressure is built up.

The high-pressure pump generates pressure to maintain a constant level in the rail. Two valves are employed to maintain the pressure within the fuel rail at the required level:

Fuel quantity control valve
Rail-pressure control valve (see corresponding description of operation)