Pump, Fuel Injection, High Pressure: Operation
High-pressure fuel lines deliver fuel under extreme pressure from the injection pump to the injectors. This could be as high as 207 bar (3, 002 psi). Use extreme caution when inspecting for high-pressure fuel leaks. Inspect for high-pressure fuel leaks with a sheet of cardboard. Wear safety goggles and adequate protective clothing when servicing fuel system. Fuel under this amount of pressure can penetrate skin causing serious or fatal injury.
The high pressure fuel pump is directly operated by the camshaft. The Powertrain Control Module (PCM) controls the Fuel Quantity Solenoid (FQS) with a Pulse Width Modulated (PWM) signal synchronized to the camshaft position. A roller cup is used between the cam lobe and the pump plunger stem to reduce friction. The pump inlet valve is normally open, allowing fuel to flow into and out of the pump as the plunger moves down and up. When the PCM determines that the remaining portion of the plunger upstroke would result in the correct volume of fuel required to maintain rail pressure, it supplies a PWM signal to the inlet valve, forcing it closed. The high fuel pressure to the common fuel rail and fuel injectors is regulated at approximately 200 bar (2900 psi). The PCM receives feedback from the Fuel Rail Pressure (FRP) sensor to control and monitor the pressure.
The "Fuel Adaptive Parameter Reset" and "Fuel Feed System Component Replacement" scan tool procedures should always be run after a PCM, fuel injector, fuel rail, high pressure pump or fuel pressure sensor is replaced. The procedures should be in the "Miscellaneous Functions" tab in the PCM. Failure to run the procedures may cause DTCs to set in the PCM.