A VE pump may be gear or spur-belt driven. The drive shaft is connected to a cam plate with a driving disk. The drive shaft, cam plate, and plunger all rotate together. The high spots on the cam plate are the face cams and the number of face cams equals the number of engine cylinders. As the cam plate rotates, the face cams contact the rollers causing the cam plate and plunger to move back and forth in the plunger bore. Spring pressure holds the cam plate and plunger against the rollers. The drive shaft also drives the fuel-supply pump and the governor flyweight drive gear.

At the bottom of the injection pump is the automatic advance-timing device. As fuel-supply pump pressure increases the piston moves the roller ring opposite to driveshaft rotation, advancing injection timing. Mounted outside the distributor head is a delivery valve for each cylinder, fuel-cut solenoid, and an air-bleed screw in the center.

At the top of the injection pump is a control lever, a control-lever shaft, and an overflow valve. Engine idle RPM and maximum speed can be adjusted by the idle-speed adjusting nozzle bolt and maximum-speed adjusting bolt.

Starting from the bottom, as the pump rotates the volume increases between the vanes. The increasing volume draws fuel into the supply pump. As the rotor continues to turn, a vane will uncover the outlet port. The volume between the vanes is decreasing, pressurizing the fuel. This pressurized fuel is then governed by the regulating valve.

Fuel from the outlet of the supply pump forces the piston back, compressing the regulating spring. As fuel flow from the supply pump increases, the piston is pushed further back allowing more fuel to be bypassed back to the inlet side. The speed of the supply pump and regulating-delivery valve-spring pressure determines how much fuel will be bypassed. It is important that the supply pump provide the correct pressure for the timing advance and fuel feed for the distributer plunger.