| 摘要 |
A method for controlling generation of a negative pressure in a fuel tank in an evaporative gas leakage diagnosis method is provided to measure the leaked amount of evaporative gas in a fuel tank without stopping an evaporative gas leakage diagnosis operation. A method for controlling generation of a negative pressure in a fuel tank in an evaporative gas leakage diagnosis method comprises an evaporative pressure measurement step, a negative pressure generation step, a standby step and a check step of leaked amount. The negative pressure generation step includes the steps of monitoring a pressure in a fuel tank after a canister purge valve is opened after the evaporative pressure measurement step, estimating the degree(P3) of reduction of the pressure in the fuel tank, and controlling the degree of opening of the canister purge valve such that the pressure in the fuel tank is excessively reduced based on the estimated degree of reduction of the pressure in the fuel tank.
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