Patent ID: 7255093

Claim:
An evaporation leak diagnostic device for detecting a fuel vapor leak in an internal combustion engine having an evaporation purge system that includes a fuel tank and a communicating tube, which connects a canister for adsorbing and retaining fuel vapor to an intake pipe, the evaporation leak diagnostic device comprising: pressure detection means for detecting the pressure of the evaporation purge system; shutout means for shutting out the evaporation purge system from atmospheric air; a pump for pressurizing or depressurizing the evaporation purge system; and leak judgment means comprising a control unit which drives the pump while the shutout means shuts out the evaporation purge system from atmospheric air, stops the pump when the pressure detected by the pressure detection means reaches a predetermined level, and formulates a leak judgment in accordance with the time the pump is driven and a pressure change encountered after pump stoppage.