FE120 L4-4.9L DSL Turbo (2005)
CAUTION: Be sure to connect the MPROP (injection quantity adjustment valve) connector to the engine harness before starting the engine.
If the engine were started with the MPROP connector not connected, control of the supply pump by the engine electronic control unit would
not be possible and a fault would ensue.
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The supply pump pressurizes fuel and supplies it in a highly pressurized state.
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Fuel drawn from the fuel tank by the feed pump is not supplied directly to the plungers. It is supplied first to the MPROP (injection quantity
adjustment valve), which controls the amount of fuel reaching the plungers.
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If the fuel pressure exceeds a certain level, the overflow valve returns fuel to the inlet side of the feed pump. This operation keeps the fuel
pressure constant.
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Rotation of the eccentric drive shaft causes (via the tappets) up-down movement of the plungers. Fuel in the plunger chambers is thus highly
pressurized.
1. MPROP (injection quantity adjustment valve)
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The MPROP receives fuel from the feed pump and feeds fuel toward the plungers of the supply pump in such a quantity that the fuel
pressure corresponds to that required by the engine electronic control unit.
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When the MPROP is not operating, i.e., when current is not flowing, fuel flows at its maximum rate. When current flows, the piston in the
MPROP is pressed down such that fuel is not fed toward the plungers.
