Patent ID: 7523743

Claim:
A system for determining a drop in fuel rail pressure due to injection of fuel into an internal combustion engine, comprising: a fuel inlet metering valve having an inlet fluidly coupled to a source of fuel, a fuel pump having an inlet coupled to an outlet of the fuel inlet metering valve, a fuel rail coupled to an outlet of the fuel pump, a pressure sensor fluidly coupled to the fuel rail and configured to produce a pressure signal indicative of fuel pressure within the fuel rail, a plurality of fuel injectors fluidly coupled to the fuel rail, and a control circuit including a memory having instructions stored therein that are executable by the control circuit to disable fuel flow from the source of fuel to the fuel rail by closing the fuel inlet metering valve, to select one of the plurality of fuel injectors to inject fuel into the engine while inhibiting fuel injection by remaining ones of the plurality of fuel injectors, to periodically sample the pressure signal, to activate the selected one of the plurality of fuel injectors to inject fuel into the engine, to determine from the samples of the pressure signal a first value of the fuel rail pressure when the selected one of the plurality of fuel injectors is activated, to deactivate the selected one of the plurality of fuel injectors to stop injection of fuel into the engine, to determine from the samples of the pressure signal a second value of the fuel rail pressure when the selected one of the plurality of fuel injectors is deactivated, and to compute a rail pressure drop value, corresponding to a drop in pressure of the fuel rail due to injection of fuel by the selected one of the plurality of fuel injectors, based on the first and second fuel rail pressure values.