| 摘要 |
PROBLEM TO BE SOLVED: To provide a system that diagnoses the presence or absence of leakage of fuel from a liquid submerged portion of a fuel tank for an internal combustion engine.SOLUTION: When a fuel surface level SGL is decreased (YES in S308) while no fuel is consumed (Fm=OFF: NO in S306), it is determined that there is fuel leakage from the liquid submerged portion of the fuel tank. However, when abnormal fuel vapor leakage is determined (YES in S311), it is not clear whether it is caused by fuel vapor leakage or fuel leakage of the liquid submerged portion. If the fuel surface level SGL is not reduced (NO in S308), it may not be influenced on the fuel surface level SGL in spite of abnormal fuel vapor leakage. When abnormal fuel vapor leakage is determined (YES in S311), determination (S312) on abnormal fuel leakage on the liquid submerged portion cannot be performed, while determination on normal fuel leakage on the liquid submerged portion can be performed (S310). Fuel leakage on the liquid submerged portion of the fuel tank can be determined, and further, diagnostic frequency for fuel leakage on the liquid submerged portion can be raised. |
