Identifying fuel system degradation
First Claim
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1. A method of operating a fuel system, comprising:
- applying a pulse to a fuel pump responsive to detecting that lift pump pressure corresponds to a fuel vapor pressure;
ceasing application of the pulse responsive to detecting that the lift pump pressure corresponds to a relief setpoint pressure; and
indicating degradation in the fuel system if the detected lift pump pressure deviates from an expected lift pump pressure, including distinguishing among degradation in the fuel pump, a lower pressure fuel pressure sensor, a fuel rail pressure sensor, and a pressure relief valve.
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Abstract
Various methods are thus provided for identifying degradation in a fuel system. In one embodiment, a method of operating a fuel system comprises applying a pulse to a fuel pump responsive to detecting that lift pump pressure corresponds to a fuel vapor pressure, ceasing application of the pulse responsive to detecting that the lift pump pressure corresponds to a relief setpoint pressure, and indicating degradation in the fuel system if the detected lift pump pressure deviates from an expected fuel rail pressure, including distinguishing among degradation in the fuel pump, a lower pressure fuel pressure sensor, a fuel rail pressure sensor, and a pressure relief valve.
47 Citations
20 Claims
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1. A method of operating a fuel system, comprising:
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applying a pulse to a fuel pump responsive to detecting that lift pump pressure corresponds to a fuel vapor pressure; ceasing application of the pulse responsive to detecting that the lift pump pressure corresponds to a relief setpoint pressure; and indicating degradation in the fuel system if the detected lift pump pressure deviates from an expected lift pump pressure, including distinguishing among degradation in the fuel pump, a lower pressure fuel pressure sensor, a fuel rail pressure sensor, and a pressure relief valve. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of operating a fuel system, comprising:
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determining an expected pressure; performing a first diagnostic by driving a lift pump in the fuel system to the expected pressure and comparing a measured pressure to the expected pressure, the lift pump driven according to an intermittent operation mode; and identifying degradation in the fuel system based on the comparison. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method of operating a fuel system, comprising:
identifying degradation in the fuel system by performing at least one diagnostic in which a lift pump of the fuel system is driven to an expected pressure and a measured pressure is compared to the expected pressure, the lift pump driven according to an intermittent operation mode. - View Dependent Claims (20)
Specification