100 has a function block 102 that contains a table curve or algorithm that relates fuel flow to the pressure drop across the fuel nozzles 68 70 and fuel divider 66 this relationship is predetermined and programmed into the control system 100 the function block 102 generates a u03b4p signal indicative of this pressure drop this u03b4p signal is added to the p 3 signal in summer 104 to arrive at a signal indicative of the output pressure pn of the ecology and pressurizing valve 62 in a summer 106 the pn signal is added to a u03b4pother signal indicative of the pressure drops across the ecology and pressurizing valve 62 and the flow meter 58 this u03b4pother signal is programmed into the control system 100 and is determined through a calibration process familiar to those skilled in then art the u03b4pother signal is added to the pn signal in summer 106 to arrive at a signal ppd indicative of the high pressure pump 56 discharge pressure using the ppd signal and the n signal function block 108 generates a signal wpd indicative of the fuel flow from the high pressure pump 56 function block 108 contains a table curve or algorithm that relates these parameters to wpd this relationship is programmed into the system 100 and is available from the pump manufacturer or can be determined through a calibration test on the pump 56 the wpd.