| 摘要 |
In an evaporated fuel gas purging system, an accurate diagnosis can be realized by providing a reference leakage apparatus (a gauge) having a preset amount of leakage, by intentionally causing a known leakage using the gauge means under the same condition of diagnosing a leakage, and by comparing the pressure change with the pressure change in using the reference leakage apparatus. In the process of diagnosing leakage by depressurizing or pressurizing and closing the inside of the evaporated fuel gas purging system so as to leave it under presence of pressure differences to the atmospheric pressure and then by detecting the pressure change, a difference occurs in the pressure changes inside the evaporated fuel gas purging system between when the gauge is opened and closed. Then sensitivity of the difference in the pressure changes to the leakage is improved under the condition during diagnosis such as fuel temperature, atmospheric pressure, amount of remaining fuel, fuel properties and so on. The accuracy of leakage diagnosis of the evaporated fuel gas purging system can be improved by removing the effect of evaporation of the fuel inside the tank.
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