Fuel system diagnostics
First Claim
Patent Images
1. A method for a vehicle fuel system, comprising:
- during a fuel system leak test, and in response to unintended temporary closing of a mechanical valve coupled to a fuel tank, not completing the fuel system leak test.
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Accused Products
Abstract
Methods and system are provided for identifying unintended closing (or corking) of a mechanical valve coupled to a fuel tank. If tank vent valve corking is identified during a leak test, fuel tank pressure data collected during the leak test is disregarded and not used to determine a fuel system leak. Instead, a fuel system leak test is repeated to improve reliability of test results.
21 Citations
20 Claims
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1. A method for a vehicle fuel system, comprising:
during a fuel system leak test, and in response to unintended temporary closing of a mechanical valve coupled to a fuel tank, not completing the fuel system leak test. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for a vehicle fuel system, comprising:
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opening a purge valve use engine intake vacuum to pull down fuel tank; in response to a pressure inflection during a first vacuum pull-down, closing the purge valve, releasing vacuum from the fuel tank, and not identifying fuel system leaks based on a first fuel tank vacuum bleed-up immediately following the first vacuum pull-down; and in response to no pressure inflection during a second vacuum pull-down, closing the purge valve to isolate the fuel tank, and identifying fuel system leaks based on a second fuel tank vacuum bleed-up immediately following the second vacuum pull-down. - View Dependent Claims (12, 13)
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14. A method for a fuel system coupled to a vehicle engine, comprising:
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opening a purge valve to pull down engine intake vacuum in a fuel tank; after applying the vacuum, closing the purge valve to isolate the fuel tank and release vacuum; in response to a pressure inflection during a first vacuum bleed-up, not identifying fuel system leaks based on the first vacuum bleed-up; and in response to no pressure inflection during a second vacuum bleed-up, identifying fuel system leaks based on the second vacuum bleed-up. - View Dependent Claims (15, 16)
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17. A vehicle fuel system, comprising:
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an engine including an intake manifold; a fuel tank coupled to the intake manifold via a canister, the fuel tank including a mechanical vent valve; a purge valve coupled between the intake manifold and the canister and configured to enable an intake manifold vacuum to be applied on the fuel tank via the canister; a canister vent valve coupled to the canister and configured to isolate the fuel system from atmosphere; and a controller with computer readable instructions for, closing the canister vent valve; opening the purge valve with the mechanical vent valve assumed open to pull down a threshold amount of intake manifold vacuum on the fuel tank; after vacuum pull-down, closing the purge valve to bleed-up vacuum from the fuel tank; in response to a pressure inflection during the vacuum pull-down, indicating unintended temporary closing of the mechanical vent valve and not identifying a fuel system leak based on the vacuum bleed-up; and in response to no pressure inflection during the vacuum pull-down, identifying a fuel system leak based on the vacuum bleed-up. - View Dependent Claims (18, 19, 20)
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Specification