Patent ID: 6631635
Filing Date: 2003-10-14
Classification: F02M

Abstract:
In an evaporation purge system including:a fuel tank; a canister having an intake hole; a purge control valve provided in a purge passage connecting said canister and an intake system of an internal combustion engine; and a purge vent valve for opening and closing the intake hole of said canister, a fault diagnostic apparatus of an evaporation purge system, comprising: tank internal pressure detecting means for detecting internal pressure of said fuel tank; valve control means for controlling closing and opening of said purge control valve and said purge vent valve; purge control valve fault detecting means for detecting a fault of said purge control valve on the basis of detected output of said tank internal pressure detecting means, at the time of the closed state of said purge control valve and said purge vent valve; and purge vent valve fault detecting means for detecting a fault of said purge vent valve on the basis of detected output of said tank internal pressure detecting means, at the time of the opening state of said purge control valve and said purge vent valve, wherein said purge vent valve fault detecting means performs fault detection of said purge vent valve, only when said purge control valve fault detecting means judges that said purge control valve is normal.