| 摘要 |
PROBLEM TO BE SOLVED: To accurately diagnose a failure in opening of a closure valve 21 during operation of an internal combustion engine 1.SOLUTION: An evaporation fuel treatment device using a canister 3 includes a purge control valve 23 and a drain cut valve 26, and also includes a closure valve 21 for changing over to communication and shutoff between a fuel tank 2 and the canister 3. The closure valve 21 comprises a normally-closed solenoid valve and opens only during fuel supply. While purging takes place, a fuel component concentration of a purge gas is detected according to an air-fuel ratio sensor 32, and if the fuel content concentration of the purge gas is richer than a reference, the closure valve 21 is determined to be in a failure in opening. A suction negative pressure is applied to the fuel tank 2 to increase evaporation fuel if the closure valve 21 has a failure in opening during the purging, and thereby the failure can be surely detected. |
