| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and a device for diagnosing a failure of an evaporated fuel treatment system capable of accurately recognizing the size of a hole, especially, accurately recognizing that the size of the hole is relatively large when a defect such as the hole is formed on a fuel tank. SOLUTION: A condition where a selector valve of an OBD pump module 17 is opened to atmospheric air and a purge VSV 14a is closed and a condition where the selector valve 17f is opened to atmospheric air and the purge VSV 14a is opened are alternately changed over for each predetermined period of time during operation of the engine, and pressure change in a system due to the change over operation is detected by a system inner pressure sensor. The detected pressure change is differentiated and it is judged whether a failure such as a hole has occurred on a canister 11 or a fuel tank 3 based on whether the differential value exceeds a predetermined threshold. COPYRIGHT: (C)2007,JPO&INPIT
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