Patent ID: 7788015

Claim:
In a fuel system having a source of fuel coupled to a plurality of fuel injectors via a fuel rail, a method for estimating a quantity of fuel injected into an internal combustion engine, the method comprising: disabling fuel flow from the source of fuel to the fuel rail, monitoring a fuel request corresponding to a request for delivery of fuel by the fuel system to the engine, and if the fuel request is below a threshold fueling level: controlling a selected one of the plurality of fuel injectors to inject a selected quantity of fuel from the fuel rail into the engine while inhibiting fuel injection by remaining ones of the plurality of fuel injectors, sampling fuel rail pressure, determining from the fuel rail pressure samples a drop in the fuel rail pressure resulting from injection of the selected quantity of fuel, and estimating the quantity of fuel injected by the selected one of the plurality of fuel injectors as a function of the drop in the fuel rail pressure resulting from injection.