Operation Section
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(3) Component Part Functions
• The HP4 supply pump component parts and functions are basically the same as for the HP3. The explanations below
only cover those points on which the HP4 differs from the HP3. For other parts, see the appropriate item in the expla-
nation of the HP3.
Pump Unit (Eccentric Cam, Ring Cam, Plunger)
• A triangular ring cam is installed on the eccentric cam on the drive shaft, and three plungers are installed to the ring
cam at intervals of 120°.
Component Parts Functions
Feed Pump Draws fuel from the fuel tank and feeds it to the plunger.
Regulating Valve Regulates the pressure of the fuel in the supply pump.
SCV (Suction Control Valve) Controls the quantity of fuel that is fed to the plungers.
Pump Unit
Eccentric Cam Actuates the ring cam.
Ring Cam Actuates the plunger.
Plunger Moves reciprocally to draw and compress fuel.
Suction Valve Prevents reverse flow of compressed fuel into the SCV.
Delivery Valve Prevents reverse flow from the rail of the fuel pumped from the plunger.
Fuel Temperature Sensor Detects the fuel temperature.
Ring Cam
Plunger
Camshaft
Eccentric Cam
Q000851E
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