Based on the inputs from the fuel pump control module (FPCM), the timing solenoid valve pulses to vary the pressure to move the timing piston, which results in the cam ring moving to the desired position to achieve the commanded timing. As pump speed increases, the fuel pressure to the timing piston assembly also increases. The amount of fuel pressure in the timing piston assembly housing is controlled by an internal transfer pump and a pulsating timing solenoid valve. The timing piston is moved by fuel pressure. VP44 Timing Principles Timing in the VP44 is controlled by an internal timing piston coupled to a cam ring inside the pump. Generally, if the fuel injection pump is injecting fuel from one outlet, it will deliver from all outlets. A worn or damaged internal transfer pump, plunger, or fueling valve can affect the pressure and amount of fuel injected, thus reducing the power from the engine. Varying the timing relative to engine speed.Ī cam ring with three plungers, a rotor, and an electronically controlled fueling solenoid valve is used to develop and distribute the high pressure required for injection.Distributing the high-pressure, metered fuel to each cylinder at the precise time.Metering the exact amount of fuel for each injection cycle.Producing the high fuel pressure required for injection.The fuel injection pump (VP44) is an electronic rotary distributor pump. VP44 - Remanufactured by certified Bosch Technicians for the 1998.5-2002 Dodge Ram Cummins Auto/5 speed Transmission.