Patent ID: 7469686

Claim:
A leak detecting apparatus comprising: an evaporation system in which a fuel vapor evaporated in a fuel tank flows, the evaporation system including a canister for adsorbing the fuel vapor in such a way that the fuel vapor can be desorbed; a measure passage; a pump connecting with the canister through the measure passage; a pressure sensor for measuring a pressure in the measure passage; and a detector for detecting a leak of the fuel vapor from the evaporation system toward an outside thereof based on the pressure measured by the pressure sensor while the pump depressurizes the evaporation system, wherein the detector determines that a discharge of the fuel vapor from the canister, the adsorbed amount of the fuel vapor in the canister being close to an upper limit of a canister adsorbing capacity, to the measure passage is detected when the pressure measured by the pressure sensor is varied from a negative pressure toward an atmospheric pressure, and forcibly terminates the depressurization of the evaporation system when the discharge of the fuel vapor is detected during a leak detecting process.