SUPPLY PUMP <4M4>

• Feed pump: Draws fuel from the fuel tank.
  
• Regulator valve: Opens when the fuel pressure between the feed pump and the suction control valve exceeds a predetermined value, and returns excess pressure to the fuel tank.
  
• Suction control valve: Regulates the amount of fuel that is delivered to the common rail in accordance with the actuation signals received from the engine-ECU.
  
• Plunger: Pressurizes the fuel that is stored in the high-pressure chamber. The plunger moves constantly at full stroke.
  
• Suction valve: Prevents the fuel in the high-pressure chamber from flowing backwards.
  
• Delivery valve: Prevents the fuel in the common rail from flowing back towards the supply pump.
  

CONSTRUCTION DESCRIPTION

Suction control valve is installed in the fuel passage between the feed pump and the suction valve. A type of solenoid valve in which the opening of the valve varies in accordance with the amount of the actuating current, the suction control valve regulates the amount of fuel that is delivered by the feed pump to the high-pressure chamber. When the amount of actuating current is small, the opening of the suction control valve becomes large, thus increasing the amount of fuel that is delivered to the high-pressure chamber. As a result, the amount of fuel that is pumped to the common rail is increased. When the amount of actuating current is large, the opening of the suction control valve becomes small, thus reducing the amount of fuel that is delivered to the high-pressure chamber. As a result, the amount of fuel that is pumped to the common rail is reduced. By varying the amount of actuating current to the solenoid valve in accordance with the running conditions of the engine, the engine-ECU controls the amount of fuel that is delivered to the high-pressure chamber.