Patent ID: 7302938

Claim:
A method for operating an automotive engine comprising fuel injectors that open to deliver fuel to the engine, said method comprising: providing a mechanical returnless fuel system for supplying fuel to the fuel injectors and including a fuel pump having a pump output, wherein the pump output is substantially constant; providing a controller for regulating an opening time for the fuel injectors to deliver a precise quantity of fuel; providing a diaphragm-less regulating valve disposed within a fuel tank for returning a portion of said pump output to the fuel supply, said diaphragm-less regulating valve outputting a non-constant linear output pressure to said fuel injectors; determining a projected engine fuel demand, said pressure regulating valve producing a fuel pressure that varies as a function of engine fuel demand; determining an estimated fuel pressure of said mechanical returnless fuel system in response to the projected engine fuel demand, said projected engine fuel demand correlating to a fuel flowrate, said determination of an estimated fuel pressure is based on a fuel pressure-fuel flow rate relationship where said fuel pressure varies linearly with said fuel flow rate; and determining an opening time for said fuel injectors based upon the estimated fuel pressure.