Abstract: A pump-line-nozzle fuel injection system in which a supply pump is coupled to a high pressure pump having a plurality of pumping cylinders, each of which has a cam-driven timing plunger and a floating metering plunger. During the retraction stroke, flow to a timing chamber formed between the pistons is blocked by a solenoid valve while the fuel passes into a metering chamber, at the discharge side of the pump, which is closed relative to the high pressure delivery line by a delivery valve. Once the proper quantity of fuel has been metered, the solenoid valve opens allowing fuel to flow into the metering chamber, balancing the pressure on opposite sides of the metering piston, so as to prevent the metering plunger from retracting further as the timing plunger continues to retract. During the compression stroke, at the appropriate time for commencement of injection, the solenoid valve recloses creating a hydraulic link between the metering and timing plungers, so that the fuel is pressurized.