FAILURE DIAGNOSTIC DEVICE FOR EVAPORATION PURGE SYSTEM

摘要

PROBLEM TO BE SOLVED: To prevent erroneous determination for a failure due to sloshing, so as to surely make judgement of a failure even in any operating condition. SOLUTION: Diagnosis of an evaporation purge system in accordance with a pressure in an evaporation passage detected by a pressure sensor 25 is permitted under such a condition that a pressure reducing process which is effected in the evaporation passage by a negative pressure produced in an intake pipe 11 by closing a vent control valve 20 provided in an exhaust pipe 21 led from a canister 17, and a pressure recovery process in which a pressure is recovered in the evaporation passage by closing a purge control valve 18 provided in a supply pipe 19 are repeated by several times.