• The HP4 basic supply pump construction is the same as for the HP3. The composition is also the same as the HP3,
being made up of the pump unit (eccentric cam, ring cam, plunger), the SCV (suction control valve), the fuel temperature sensor, and the feed pump. The main difference is that there are three plungers.
• Because there are three plungers, they are positioned at intervals of 120? around the outside of the ring cam. In addition, the fuel delivery capacity is 1.5 times that of the HP3.
• The fuel discharge quantity is controlled by the SCV, the same as for the HP3.
