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Methods and apparatus are provided for testing a fuel pump in a fuel supply system on a IC fuel injected engine, the pump having a pumping element for supplying fuel injectors via a fuel rail. The method includes providing a pump element pumping event; disabling overlapping injectors during a test-p

Methods and apparatus are provided for testing a fuel pump in a fuel supply system on a IC fuel injected engine, the pump having a pumping element for supplying fuel injectors via a fuel rail. The method includes providing a pump element pumping event; disabling overlapping injectors during a test-period that includes the pumping event; measuring pressure in the rail at least two engine crank angles surrounding the pumping event during the test period; and determining a fuel delivery rate value for the pump based on the measured rail pressures. Methods and apparatus also are provided for determining quantitative leakage rate in the fuel supply system of a fuel injected IC engine, the fuel system including a fuel pump with one or more pumping elements supplying injectors via a fuel rail. The method includes establishing steady state engine operating conditions with fuel rail pressure at a predetermined value; disabling all overlapping injectors and all pumping events during a test period; measuring rail pressure at preselected first and second crank angles during the test period, the first crank angle being advanced relative to the second crank angle; and calculating the leakage rate based on a pressure drop determined from the measured rail pressure at the first crank angle and the measured rail pressure at the second crank angle.

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What is claimed is: 1. A method for testing a fuel pump in a fuel supply system on a IC fuel injected engine, the pump having a pumping element for supplying fuel injectors via a fuel rail, the method comprising: (a) providing a pump element pumping event; (b) disabling overlapping injectors during

What is claimed is: 1. A method for testing a fuel pump in a fuel supply system on a IC fuel injected engine, the pump having a pumping element for supplying fuel injectors via a fuel rail, the method comprising: (a) providing a pump element pumping event; (b) disabling overlapping injectors during a test period that includes the pumping event; (c) measuring pressure in the rail at least two engine crank angles surrounding the pumping event during the test period; and (d) determining a fuel delivery rate value for the pump based on the measured rail pressures. 2. The method as in claim 1, further including comparing the pump fuel delivery value with a predetermined pump fuel delivery rate requirement. 3. The method as in claim 1, wherein determining the fuel delivery rate value includes calculating the fuel delivery rate value based on one or more parameters selected from a fuel rail system volume, a fuel bulk modulus, and an engine coolant temperature. 4. The method as in claim 1, wherein determining the fuel delivery rate value includes adjusting for fuel rail leakage. 5. The method as in claim 1, wherein the pump has multiple pump elements, and wherein the method further comprises repeating method elements (a)-(c) for each other pump element, and wherein element (d) includes determining fuel delivery rate values for each pump element based on the respective measured rail pressures and adding the fuel delivery rate values to determine the pump fuel delivery rate value. 6. The method as in claim 1, wherein method elements (a)-(c) are carried out during normal operation of the engine. 7. The method as in claim 1, wherein the fuel supply system includes a pump valve having a variable opening timing angle, for controlling fuel delivery to the rail, and wherein the method includes preliminary setting the pump valve timing angle to achieve maximum pump element delivery rate. 8. The method as in claim 7, wherein the method includes repeating method elements (a)-(d) with the pump valve timing set to achieve a lower pump element delivery rate. 9. The method as in claim 7, wherein the method further includes comparing the determined maximum pump delivery rate with a rate leakage determined for the particular system with the installed pump, and determining whether a predetermined acceptable maximum pump delivery rate/system leakage rate condition exists. 10. Apparatus for testing a fuel pump in a fuel supply system on a fuel injected IC engine, the pump having a pumping element for supplying fuel injectors via a fuel rail, the apparatus comprising: a computer programmed with (a) software for providing a pump element pumping event; (b) software for disabling overlapping injectors during a test period that includes the pumping event; (c) software for measuring pressure in the rail at least two engine crank angles surrounding the pumping event during the test period; and (d) software for determining a pump fuel delivery rate value based on the measured rail pressures, wherein the computer is operatively interconnectable to the engine. 11. The apparatus as in claim 10, wherein the IC engine includes an engine control module (ECM) having a microcontroller programmed with an engine control program, and wherein the programmed computer is operatively connectable to the ECM. 12. The apparatus as in claim 11, further comprising a service tool, wherein the programmed computer is interconnectable to the ECM through the service tool. 13. The apparatus as in claim 11, wherein fuel supply system includes a pump valve having a variable opening timing angle, wherein an engine control module (ECM) controls the timing angle setting, and wherein the software for providing a pump element pumping event includes software for preliminarily causing the ECM to set the pump valve timing to achieve a fuel delivery value selected from a predetermined high value delivery rate and a predetermined low delivery rate value. 14. The apparatus as in claim 13, wherein the pump valve is solenoid-activated, wherein the ECM includes start of current (SOC) timing angles, and wherein the computer includes software for causing the ECM to set the soc angle to achieve, respectively the high or lower pump element delivery rate values. 15. The apparatus as in claim 10, wherein the software for disabling overlapping injectors also includes software for disabling overlapping pumping events during the test period. 16. The apparatus as in claim 10, wherein the programmed computer is a stand-alone test unit and an engine control module (ECM) computer. 17. A method for determining a quantitative leakage rate in a fuel supply system of a fuel injected IC engine, the fuel system including a fuel pump with one or more pumping elements supplying injectors via a fuel rail, the method comprising: (a) establishing steady state engine operating conditions with fuel rail pressure at a predetermined value; (b) disabling all injectors and all pumping events during a test period; (c) measuring rail pressure at preselected first and second crank angles during the test period, the first crank angle being advanced relative to the second crank angle; and (d) calculating the leakage rate based on a pressure drop determined from the measured rail pressure of the first crank angle relative to the measured rail pressure at the second crank angle. 18. The method as in claim 17, wherein the calculation is based on one or more parameters selected from a fuel rail system volume, a fuel bulk modulus, and an engine coolant temperature. 19. The method as in claim 17, wherein (i) the disabled injectors and pumping events are reinstated, and (ii) method elements (a)-(d) are repeated at a different predetermined rail pressure value. 20. The method as in claim 17, wherein the engine includes an ECM having a fuel rail pressure control function, and wherein establishing steady state conditions includes using the rail pressure control function to provide the predetermined rail pressure value.