| 摘要 |
PROBLEM TO BE SOLVED: To prevent an evaporation gas from being emitted to the atmosphere by surely executing the leak diagnosis of an evaporation gas purge system with a sufficient frequency and executing leak diagnosis during an interruption of an engine. SOLUTION: When the engine is operated, the leak diagnosis is executed by introducing a negative pressure from an engine intake system into an evaporation system ranging from a fuel tank 11 to a purge control valve 15 every time when a specified leak diagnosis execution condition is established. On the other hand, while the engine is not operated, the leak diagnosis is executed by introducing a negative pressure into the evaporation system by a negative pressure pump installed in a leak check module 17 when a predetermined time elapses after an IG switch 33 is turned off, but the leak diagnosis is inhibited when the concentration of the evaporation gas within the evaporation system is high during an interruption of the engine. Thus, while the evaporation gas of a high concentration is prevented from being emitted to the atmosphere during the interruption of the engine, the leak diagnosis both during the operation of the engine and during the interruption of the engine is executed so that the leak diagnosis can be executed with a sufficient frequency. COPYRIGHT: (C)2005,JPO&NCIPI
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