Patent ID: 6397824
Filing Date: 2002-06-04
Classification: F02D,F02M

Abstract:
A fault diagnosing apparatus for evapopurge systems, adapted to have a transpiration gas occurring in a fuel tank adsorbed to a canister via a vapor passage communicating the fuel tank and canister with each other, and purge the canister of the fuel adsorbed thereto and discharge the resultant fuel into a suction passage of an internal combustion engine via a purge passage communicating the canister and suction passage with each other, comprising:a device adapted to detect a pressure in the interior of an evapopassage including the fuel tank, a depressurization device adapted to close a first valve provided in an atmosphere-opened port of the canister and depressurize the interior of the evapopassage by a negative pressure occurring in the suction passage, a repressurization device adapted to close a second valve, which is provided in the purge passage, after the operation of the depressurization device finishes, to repressurize the interior of the evapopassage, and a fault judgement device adapted to allow a judgement, which is based on an output from the pressure detecting device, that an evapopurge system is abnormal to be given on condition that the depressurization and repressurization devices are operated plural times.