Diesel Fuel System

DIESEL FUEL SYSTEM

Electro-Hydraulic Injector






The electro-hydraulic injector is composed of 3 major components: The oil control, the pressure amplification, and the nozzle assembly. The injector uses 2, 48-volt at 20-amp coils to control a spool valve that directs oil flow in and out of the injector. The fuel injector has a self-extracting hold-down clamp.

Electro-Hydraulic Injector Amplifier Piston
The high pressure oil flows from the oil rails into an electro-hydraulic injector amplifier piston located in the injector. Oil entry and exit to and from the amplifier piston is controlled by a coil-operated spool valve.

Electro-Hydraulic Injector Fuel Plunger
The electro-hydraulic injector fuel plunger is located in the injector and is driven by the amplifier piston. The fuel plunger injects fuel into the combustion chamber at pressures of up to 196,500 kPa (28,500 psi) through the nozzle assembly. Fuel is supplied to the injector at approximately 345 kPa (50 psi) through fuel rails in the cylinder heads.

Engine Timing
The powertrain control module (PCM) commands the fuel quantity. The fuel injector control module (FICM) controls the duration of the injection event and is shown as parameter identification (PID) FUELPW on the scan tool.

The PCM controls the injection pressure and fuel volume by varying the injection oil pressure with the injection pressure regulator (IPR). The command to the IPR is a 12-volt, pulse width modulated (PWM) signal controlled on the ground side.

The injection oil pressure command is shown as PID IPR which is the percentage ON of the PWM signal. The injection oil pressure is shown as PID ICP.

The PCM uses camshaft position (CMP) and crankshaft position (CKP) input signals to calculate the engine speed and position. The PCM conditions both input signals and supplies the FICM with the CMP and CKP output signals. The FICM uses the CMP and CKP output signals to determine the correct sequence for injector firing. The PCM sends information about the fuel demand, engine oil temperature (EOT), and injection control pressure (ICP) through the CAN to the FICM. The FICM uses this information to calculate the injection cycle.

Fueling Corrections
The PCM adjusts the injector output based on the oil temperature information received from the EOT sensor and turbo boost information received from the manifold absolute pressure (MAP) sensor and the barometric pressure (BARO) sensor. These corrections are necessary to meet emissions requirements and to optimize power. The engine coolant temperature (ECT) and the EOT sensors are used as the primary input to the PCM to enable adaptive cooling. This provides a means of providing adequate cooling in severe engine temperature conditions. When the engine coolant temperature is greater than 105°C (221°F) or the engine operating temperature is greater than 123°C (253°F), the fueling rate of the engine is modified to provide cooling protection and prevent engine damage due to overheating. Outputs of these sensors can be monitored using a scan tool reading PIDs.

Fuel Injector Control Module (FICM)
The coil-operated spool valve requires 48 volts at up to 20 amps to operate, which is more power than the PCM can supply. Therefore, a high power device, the FICM, is used to supply power to the solenoid on command from the PCM.

Fuel System

Fuel System - 6.0L:

Fuel is drawn from the fuel tank through the primary filter (located in the horizontal fuel conditioning module) by the electric fuel pump. Pressurized fuel, approximately 310-379 kPa (45-55 psi), is supplied to the secondary filter (the fuel filter housing located on the front left side of the engine) by means of the electric pump and regulator valve. The regulator relieves the pressure, sending fuel back to the fuel tank. Only the filtered fuel going through the fuel filter goes to the heads. A check valve is located on both heads to prevent fuel pressure spikes in the fuel rail.

High Pressure Oil System







The 6.0L diesel fuel injectors are powered by lubricating oil which is pressurized by a high pressure pump in the engine valley. The pump output pressure ranges from 3,102 to 27,579 kPa (450 psi to 4,000 psi). Oil pressure is controlled by the PCM through the injection pressure regulator (IPR) valve. The PCM controls pressure in the oil rail by opening (relieving pressure) and closing (increasing pressure) the IPR valve. The high pressure oil is delivered to the oil rails in the cylinder heads. An injection control pressure (ICP) sensor mounted on the high pressure pump cover sends an analog voltage signal (0.5 to 5.0 volts) to the PCM for feedback control of the oil pressure.