A fuel system, comprising: a fuel source; a variable displacement fuel pump, including: a pump body; a barrel disposed within the pump body; at least one piston disposed in the barrel, wherein the at least one piston is configured to reciprocate within the barrel to provide a fuel flow; and an electronic control actuator operatively coupled to the barrel, wherein the electronic control actuator rotates the barrel to a selected barrel angle relative to the at least one piston in response to a desired fuel flow parameter; a controller to receive a thrust demand parameter to provide the desired fuel flow parameter to the electronic control actuator; and a thrust output device to receive the fuel flow to provide a thrust output corresponding to the thrust demand parameter; a high-pressure relief valve connected between the variable displacement fuel pump and the thrust output device; a mass fuel metering sensor connected between the high-pressure relief valve and the thrust output device; and a fuel flow pressure sensor connected between the mass fuel metering sensor and the thrust output device; wherein the controller is configured to select the barrel angle to provide a desired fuel flow rate in response to the thrust demand parameter, fuel mass of the fuel flow reported by the mass fuel metering sensor, and pressure of the fuel flow reported by the fuel flow pressure sensor to limit fuel flow returned to the fuel source through the high-pressure relief valve. a fuel source; a variable displacement fuel pump, including: a pump body; a barrel disposed within the pump body; at least one piston disposed in the barrel, wherein the at least one piston is configured to reciprocate within the barrel to provide a fuel flow; and an electronic control actuator operatively coupled to the barrel, wherein the electronic control actuator rotates the barrel to a selected barrel angle relative to the at least one piston in response to a desired fuel flow parameter; a controller to receive a thrust demand parameter to provide the desired fuel flow parameter to the electronic control actuator; and a thrust output device to receive the fuel flow to provide a thrust output corresponding to the thrust demand parameter; a high-pressure relief valve connected between the variable displacement fuel pump and the thrust output device; a mass fuel metering sensor connected between the high-pressure relief valve and the thrust output device; and a fuel flow pressure sensor connected between the mass fuel metering sensor and the thrust output device; a pump body; a barrel disposed within the pump body; at least one piston disposed in the barrel, wherein the at least one piston is configured to reciprocate within the barrel to provide a fuel flow; and an electronic control actuator operatively coupled to the barrel, wherein the electronic control actuator rotates the barrel to a selected barrel angle relative to the at least one piston in response to a desired fuel flow parameter; a controller to receive a thrust demand parameter to provide the desired fuel flow parameter to the electronic control actuator; and a thrust output device to receive the fuel flow to provide a thrust output corresponding to the thrust demand parameter; a high-pressure relief valve connected between the variable displacement fuel pump and the thrust output device; a mass fuel metering sensor connected between the high-pressure relief valve and the thrust output device; and a fuel flow pressure sensor connected between the mass fuel metering sensor and the thrust output device; wherein the controller is configured to select the barrel angle to provide a desired fuel flow rate in response to the thrust demand parameter, fuel mass of the fuel flow reported by the mass fuel metering sensor, and pressure of the fuel flow reported by the fuel flow pressure sensor to limit fuel flow returned to the fuel source through the high-pressure relief valve.