3. Construction and Operation 3.1 Description of Main Components [1] Supply Pump (HP3, HP4) (1) Outline a. The supply pump consists primarily of the pump body (cam shaft, ring cam, and plungers), SCV (Suction Control Valve), fuel temperature sensor, and feed pump. b. The two plungers for HP3 or the three plungers for HP4 are positioned vertically on the outer ring cam for compactness. c. The engine drives the supply pump at a ratio of 1:1. The supply pump has a built-in feed pump (trochoid type), and draws the fuel from the fuel tank, sending it to the plunger chamber. d.
The internal camshaft drives the two plungers, and they pressurize the fuel sent to the plunger chamber and send it to the rail. The quantity of fuel supplied to the rail is controlled by the SCV, using signals from the engine ECU. The SCV is a normally opened type (the intake valve opens during de-energization). HP3 SCV Fuel Temperature Sensor Q000252E Fuel Temperature Sensor HP4 SCV Q000253E 6