High Pressure (Hp) Fuel Pump
| ITEM | DESCRIPTION |
|---|---|
| 1 | Low Pressure (LP) fuel return connection |
| 2 | Low Pressure (LP) fuel supply connection |
| 3 | Fuel temperature sensor |
| 4 | Drive shaft |
| 5 | Fuel outlet to Bank 2 fuel rail |
| 6 | Fuel metering valve |
| 7 | Fuel outlet to Bank 1 fuel rail |
The HP fuel pump is a 2 piston radial plunger pump. The pump has the ability to produce a maximum pressure of 2000 bar (29007 lbf/in2 ).
The HP fuel pump is driven from the Bank 2 cylinder head exhaust camshaft via a toothed belt. The drive from the belt rotates a cam within the pump which operates a plunger within each pumping element. A procedure and special tools are required for pump or belt replacement to time the pump. For additional information, refer to:
ENGINE (DESCRIPTION AND OPERATION)
The HP fuel pump comprises 2 HP pumping elements, a fuel metering valve, an internal transfer pump and a fuel temperature sensor.
The fuel is delivered to the internal transfer pump via the external fuel filter and an electric fuel pump which is located in the fuel tank. For additional information, refer to: FUEL TANK AND LINES
The fuel metering valve is located in the feed port between the HP pumping elements and the internal transfer pump. The fuel metering valve is a variable position solenoid-operated valve that is controlled by the ECM. The fuel metering valve determines the amount of fuel that is delivered from the internal transfer pump to the HP pumping elements. When there is no signal to the fuel metering valve, the valve is closed and there is no fuel delivery.
The fuel from the internal transfer pump is passed to the HP pumping elements at a constant pressure known as transfer pressure. The transfer pressure is controlled by an internal Pressure Relief Valve (PRV). Once the fuel enters each of the HP pumping elements the pressure rises rapidly, with each element providing a HP supply to one of the fuel rails. The pressure is controlled by the fuel rail Pressure Control Valve (PCV) and the Fuel Rail Pressure (FRP) sensor.
A controlled amount of fuel is allowed to leak-off from the internal transfer pump. This fuel cools and lubricates the internal components of the HP fuel pump, then returns to the fuel tank through the LP fuel return line.
The fuel temperature sensor is located on the rear of the HP fuel pump. It measures the fuel temperature in the LP side of the HP fuel pump. The ECM continually monitors this signal to determine the fuel temperature to prevent overheating of the fuel system. The ECM will also make fine adjustments to fuel injection quantity to adjust for fuel temperature.