| 摘要 |
A remotely actuatable diagnostic valve biased normally open is disposed in the air inlet of a vehicle fuel tank vapor storage canister and a thermistor disposed to sense vapor temperature above the liquid level in the fuel tank. Upon engine shutdown, the valve is remotely actuated to close. When the fuel vapor in the tank cools to form a vacuum in the tank, the vacuum overcomes the valve bias and holds the valve shut when the valve is remotely de-actuated. A valve position sensor provides confirmation that the valve has been held shut by the vapor vacuum when the valve is de-actuated. If a leak exists the vacuum will be insufficient to hold the valve closed after remote de-actuation; and, the valve is biased open, whereupon the valve position sensor provides a fault indication signal.
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