Fuel System Operation - 3.0L
This vehicle is equipped with a Direct Injection system. The Direct Injection system sprays fuel at a very high pressure directly into the combustion chamber. There are two sides to the fuel system, the low pressure (supply) side and high pressure (control) side.
LOW PRESSURE SIDE OPERATION: When the Powertrain Control Module (PCM) requires fuel pump operation it energizes the fuel pump relay. The battery voltage output from the relay does not connect directly to the fuel pump like traditional systems. Instead, the battery voltage is supplied to the Fuel Pump Control Module (FPCM). When the ignition is switched on, the battery voltage is present for approximately five seconds. Battery voltage should always be present during cranking or when the engine is running. The purpose of FPCM is to operate the fuel pump at a reduced voltage output to reduce electrical load on the system. The low pressure system operates as a fixed pressure system , typically around 520 kPa (75.4 psi) during normal operation. The fuel pump inside the fuel tank supplies fuel to the High Pressure (HP) fuel pump mounted on the engine. The low pressure fuel pump operates in the same manner as a typical brushed DC motor. The only difference is that the speed is reduced due to the PWM output voltage from the FPCM being less than 100%.
The standard output engines are equipped with one HP fuel pump. The high output engines are equipped with two HP fuel pumps.
HIGH PRESSURE SIDE OPERATION:
The Powertrain Control Module (PCM) regulates the pressure on the high pressure side by regulating the output volume from the engine mounted High Pressure (HP) fuel pump to the fuel rail.
The 3.0L SO engine is equipped with one HP fuel pump and the 3.0L HO engine is equipped with two HP fuel pumps to meet demand.
To control the pressure, the PCM monitors the fuel rail mounted Fuel Rail Pressure (FRP) Sensor signal feedback to determine the energized (ON) time of the Fuel Quantity Solenoid (FQS). When the FQS is energized the inlet valve is closed and the remaining fuel in the HP pump(s) is pressurized and forced passed the outlet check valve into the fuel rail. The system has the ability to operate at a pressure range of
3, 000 to 35, 00kPa (435 to 5, 076 psi)
The solenoid actuated, multi-hole fuel injector delivers the atomized fuel directly into the combustion chamber. The PCM calculates the fuel quantity that is injected and injection timing based on the signals from several engine sensors. The engine sensors with the biggest impact on fuel injection timing and quantity are:
- Oxygen (O2) Sensors
- Accelerator Pedal Position (APP) Sensor
- Boost Pressure Sensor
- Manifold Absolute Pressure (MAP) Sensor
- Intake Air Temperature (IAT) Sensor
- Engine Coolant Temperature (ECT) Sensor
- Crankshaft Position (CKP) Sensor
- Camshaft Position (CMP) Sensor
- Turbo Inlet Air Temperature Sensor
- Knock Sensors
- BARO Sensor