Evaporative system and method of diagnosing same

摘要

There is disclosed a leakage diagnosis of an evaporative system in an internal combustion engine, and more particularly there is disclosed an evaporative system in which a more accurate leakage diagnosis can be effected using a change in the pressure in the evaporative system, and such a diagnosis method is also disclosed. The evaporative system includes a gauge line having a gauge valve, which gauge line branches off from an evaporative gas line or an evaporative gas purge line, and communicates with a point upstream of an engine throttle valve or with the ambient atmosphere, a pressure sensor for detecting the pressure in the evaporative system, and a purge valve. A leakage diagnosis of this system is effected based on detected values of the pressure sensor obtained by opening and closing the purge valve and the gauge valve. Therefore, accurate results of the diagnosis can be obtained.