Patent ID: 6829921
Filing Date: 2004-12-14
Classification: F02M

Abstract:
An abnormality detecting device for an evaporative fuel processing system including:a fuel tank; a canister for trapping evaporative fuel generated in said fuel tank; a charging passage for connecting said fuel tank and said canister; a tank pressure regulating valve provided in said charging passage; a bypass passage bypassing said tank pressure regulating valve; a bypass valve provided in said bypass passage; and a pressure sensor provided in said fuel tank or in said charging passage at a position between said tank pressure regulating valve and said fuel tank, said abnormality detecting device comprising: pressure reducing means for reducing a pressure in said canister to a pressure which is lower than an atmospheric pressure in the condition where a valve closing command signal for said bypass valve is output; and diagnosing means for determining that said tank pressure regulating valve or said bypass valve is abnormal when the pressure detected by said pressure sensor becomes equal to or less than a predetermined threshold during execution of the pressure reduction by said pressure reducing means.