Bi-level hydraulic pressurizing system

A fuel system having a pump (108) for providing a flow of fuel and a metering valve (120) receiving the flow of fuel and providing a regulated flow of fuel consists of a bi-level hydraulic pressurization system for controlling the output pressure of a fuel supply which includes a pressure regulating valve (146) for maintaining a constant pressure differential across the metering valve. The pressure regulating valve also controls a pressure signal to a pressurization valve (144).