C7 Industrial Engines Systems Operation – Fuel System

Pump Pressure Regulator

The pump pressure regulator is internal to the unit injector hydraulic pump. The pump pressure regulator is a valve of high precision that controls pump outlet pressure (actuation pressure) by changing pump outlet flow. The performance maps in the ECM (18) contain a desired actuation pressure for every engine operating condition. The ECM sends a control current to the pump pressure regulator. The control current should make the actual actuation pressure equal to the desired actuation pressure.

The pump pressure regulator is an actuator that converts an electrical signal from the ECM to the mechanical control of plunger sleeves in order to change the pump outlet flow and the pump outlet pressure.

Fuel Transfer Pump

Illustration 3 g01447557
Unit injector hydraulic pump

(1) Unit injector hydraulic pump

(11) Fuel transfer pump

Fuel transfer pump (11) is mounted on the back of unit injector hydraulic pump (1). The fuel transfer pump is used in order to draw fuel from fuel tank (14). Also, the fuel transfer pump is used in order to pressurize the fuel to 450 kPa (65 psi). The pressurized fuel is supplied to injectors (5) .

The fuel transfer pump is a gear pump. The pump is mounted on the back of the unit injector hydraulic pump. The fuel transfer pump is driven by the shaft of the unit injector hydraulic pump. A relief valve in the fuel transfer pump limits the outlet pressure to 689 ± 69 kPa (100 ± 10 psi). Fuel is drawn from the tank to the inlet port of the pump. The rotation of the gears causes the fuel to flow out of the pump outlet port through the secondary fuel filter (12) and to the fuel supply passage (10) that is located in the cylinder head.

Injection Actuation Pressure Sensor (IAP)

Illustration 4 g01448151
(9) IAP sensor

IAP Sensor (9) is installed in the high pressure oil manifold. The high pressure oil manifold supplies actuation oil in order to power the unit injectors. The IAP Sensor monitors injection actuation pressure. The IAP Sensor sends a continuous voltage signal back to ECM (18). The ECM interprets the signal. The ECM is aware of the injection actuation pressure at all times.