A two-stage system for delivering fuel to a gas turbine including a first stage variable pump for serving as a primary source of fuel, a second stage fixed pump for selectively supplementing the variable pump, a bypass valve connected to the fixed pump for loading and unloading the fixed pump and a regulator valve assembly connected to the variable pump and the bypass valve for controlling operation of the variable pump and the bypass valve. Preferably, the two-stage system also includes a control valve connected to the regulator valve assembly for setting a pressure differential across the regulator valve assembly and, thereby, loading and unloading the fixed pump.