Mitsubishi 6M70 Workshop Manual page 137

• When the engine is cranked by means of the starter switch, the feed pump (this is located inside the supply pump)
simultaneously draws fuel from the fuel tank and feeds it via the water separator, gauze filter and fuel filter to the
MPROP (rail pressure control valve). A quantity of fuel metered by the MPROP is supplied via the inlet valves to
the plunger chambers.
• The fuel in the plunger chambers is pressurized. The outlet valves are then opened, and the fuel is fed under
pressure to the common rail.
• The pressurized fuel is held in the common rail and then uniformly fed to the injectors.
• In response to signals from the engine electronic control unit, a magnetic valve in each injector causes the injector
to inject fuel into the relevant combustion chamber at the optimal timing and in the optimal quantity.
• If fuel leakage occurs through any of the fuel line connections between the common rail and injectors, the relevant
flow limiter(s) will close, shutting off fuel supply and thus preventing any further fuel leakage out of the system.
• If the pressure of fuel in the common rail rises above the specified level, the pressure limiting valve opens to allow
fuel to return to the fuel tank.
• If the pressure of fuel in the supply pump rises above the specified level, the overflow valve opens to allow fuel to
return to the fuel tank.
• Excess fuel in the injector returns to the fuel tank through passages in the cylinder head.
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