Test Of High-Pressure Pump: Notes

The high-pressure pump in the common rail system delivers fuel under high pressure into the rail. During operation, the three pistons of the high pressure pump generate pressure peaks in the rail which can be made visible by means of measuring the rail pressure sensor signal with an oscilloscope. The shape of the signal makes it possible to determine the mechanical status of the high pressure pump.

In order to obtain a meaningful signal, the rail pressure control must  be active. The test module automatically switches from volumetric flow regulation to rail pressure control. As a result, two faults are stored in the DDE fault memory; these should be ignored and must be deleted once diagnosis has been completed.