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Common-Rail Diesel Fuel Systems
Today most new diesel engines are equipped with Common-Rail fuel injection systems. These systems use electronically controlled fuel injectors to inject fuel from a common high-pressure fuel rail, rather than a mechanical injection pump which pressurizes fuel to a fuel line which forces a single fuel injector open. These systems also differ from a 7.3L Powerstroke injection system, where low-pressure fuel is pressurized within the injector by high-pressure oil.
Ford 6.4L Common-Rail Diesel
Fuel Supply System
The fuel supply system on a Common-Rail diesel uses either an electric fuel pump or a mechanical lift pump incorporated into the high-pressure fuel pump. Fuel is drawn from the fuel tank and sent to the high-pressure fuel pump. On some systems, a Suction Control Valve controls fuel flow into the high-pressure pump, thereby regulating the pressure in the high-pressure fuel rail. This would be an example of a one-line supply system. A two-line supply system works in a similar way to a gasoline 2-line supply system, except the the fuel is delivered to the high-pressure pump rather than the fuel rail. Excess fuel is then returned to the fuel tank. On a one-line system, fuel returns to the tank from the fuel delivery side of the system.
Isuzu 5.2L Common-Rail Diesel