A fuel metering unit for controlling a variable displacement pump including a
main
metering valve in fluid communication with the pump for metering an output of the
pump, a pressure regulator in fluid communication with the metering valve to create
a spill return and a control valve in fluid communication with the pressure regulator
and the pump for regulating the spill return flow so the spill return flow is maintained
substantially constant at a low level to minimize the heat generated by recirculation
by setting a displacement of the pump.