| 摘要 |
PROBLEM TO BE SOLVED: To prevent erroneous diagnosis of boring failure of a fuel vapor system even in the case that a factor other than boring influences on the pressure in the fuel vapor system during diagnosis of boring. SOLUTION: Negative pressure generated in an internal combustion engine is introduced into a fuel vapor system including a fuel tank 7 and spaces 11, 14, 19, 20, 21, 24, 31, 26, 27, 28 communicated with an inner space of the fuel tank. Afterward, the fuel vapor system is sealed. When the pressure in the fuel vapor system exceeds a preset determination value after the specified time has passed from the sealing of the fuel vapor system, occurrence of boring failure is determined in the fuel vapor system. The operation of the internal combustion engine is stopped during introduction of the negative pressure to the fuel vapor system. |
