The fuel VCV is mounted on the top of the high pressure fuel pump. The VCV is pulse width modulated by the PCM to control the amount of fuel that enters the high pressure fuel pump. Together with the Pressure Control Valve (PCV), the VCV regulates the fuel rail pressure. The VCV also interrupts the… Read More »
The PCV is threaded into the rear of the left fuel rail. The PCV is a two wire normally open Pulse Width Modulated (PWM) solenoid. The PCM relay supplies system voltage to one wire of the solenoid. The PCM uses a pulse width modulates ground to control the PCV until the desired fuel pressure is… Read More »
The outlet check valve closes while fuel is being drawn in due to a pressure difference on the two sides of the check valve. Once the piston starts its compression stroke, the inlet check valve closes via the spring and fuel pressure and the outlet check valve opens due to increasing fuel pressure, forcing the… Read More »
The pistons are actuated via the actuating lobes and are returned to rest via spring pressure. The pistons receive fuel from the through a one- way check valve. Fuel is drawn into the cylinder while the piston is returning to rest. The fuel flow to the cylinders of the pump are metered by the Volume… Read More »
The high pressure fuel pump is a 2-cylinder design. The main shaft has two actuating lobes. The actuating lobes are offset 180 degrees from each other. Each pump piston is actuated twice per crankshaft revolution.
The high pressure fuel pump is mounted in the front valley of the engine and is gear driven by the camshaft. The high pressure fuel pump is timed to the crankshaft and camshaft to optimize the effects of the high pressure fuel pulses. The high pressure fuel pump is lubricated by diesel fuel.
The Volume Control Valve (VCV) controls how much fuel enters the two high pressure pump pistons. The high pressure fuel pump is restricted as required by the PCM. Under varying conditions the fuel system is in PCV or VCV mode. Two high pressure fuel lines from the high pressure fuel pump transport the fuel to… Read More »
The injector low pressure connectors have a dual purpose. First, it is not really a return but a low pressure feed to keep fuel pressure inside the hydraulic coupler. Without fuel pressure in the hydraulic coupler, the injector will not deliver fuel. Second, the fuel that passes through the injector during the injection process exits… Read More »
A fuel cooler is located on the left frame rail forward of the DFCM. The black fuel line is used for fuel return from the engine to the cooler. The gray fuel line returns fuel from the cooler to the DFCM. Depending on the temperature of the fuel from the injectors, the fuel cooler can… Read More »
The FRT is mounted in the fuel line that runs between the secondary fuel filter and the high pressure fuel pump. It is green in color. The PCM monitors the temperature of the fuel using the FRT before the fuel enters the high pressure fuel pump. Fuel temperature effects fuel viscosity. The PCM uses this… Read More »