LR3/Disco 3
The HPP is a three-piston (120 degree apart) radial plunger pump with a HP displacement of 0.8 cc. As mentioned, it has
the ability to produce a maximum pressure of 1650 bar. The housing is cast from iron, the flange is cast from aluminium.
The pump is driven from the camshaft via a toothed belt. It does not need to be timed to the engine during belt
replacement in service.
The required supply pressure to the HPP is -0.3 bar to +0.5 bar gauge. The return pressure is -0.3 bar to +0.8 bar gauge.
The pump is sized to deliver sufficient fuel to the HP rails for all engine-operating conditions.
The HPP consists of the following components:
Internal Transfer Pump (ITP)
Volume Control Valve (VCV)
HP pumping elements (3 of)
Pressure Control Valve (PCV)
The ITP is a 5 vane pump. This conveys fuel to the VCV.
The VCV is a variable position solenoid valve electronically controlled by the ECM. The VCV is located between the ITP
and the HP pumping elements. The VCV determines the amount of fuel that is delivered to the HP pumping elements.
When there is no signal to the VCV the valve is closed, therefore no fuel delivery.
The 3 HP pumping elements are connected together in a fuel ring circuit within the pump. There is a single HP outlet
connection for the HP pipe to the HP diverter rail.
