Common Rail Fuel System Operation High-pressure fuel as received at each injector provides lubrication and cooling of the injectors while awaiting the DDECIV signal from the ECM’s to the injector solenoid to start the injection event. Approximately 90% of the fuel received at the injectors is injected into the engine cylinder for combustion, while 10% of the fuel is returned to the fuel tank under full load conditions. Washer C-E Ring Inlet Filter Retaining Nut Fig. 6 CROSS SECTION VIEW OF FUEL SYSTEM AT CYLINDER HEAD The high-pressure fuel rails provide continuous pressure at all times to all injectors within the engine.
The high-pressure fuel rail at each cylinder location is a port, which is fitted with a flow-limiter valve. High-pressure fuel passes from the stainless steel high-pressure rails through flow limiter valves to the injectors. The flow limiter valves operate by sensing fuel flow differential, which can shut off the flow of fuel to prevent excessive over fueling of a cylinder in the event of a faulty injector (Refer to page 53). All of the joints from the high-pressure rail to the flow limiter valves to the injectors are conical shaped metal-to-metal sealing (Refer to page 37). Page 6