In order to understand how designed fuel pressures are maintained over a broad range of conditions weโll now take a closer look at regulator assembly operation.
This illustration shows the operation of the pressure regulator assembly while the pump is running. Fuel output from the discharge side of transfer pump forces the piston in the regulator assembly against the regulating spring. (Figure 4-49).
Since the fuel pressure on the piston is opposed by the regulating spring, the pressure curve of the transfer pump is controlled by the spring rate and the size of the regulating slot. This results in pressure being increased as engine speed increases. (Figure 4-50).
