To effectively utilize leak gas while preventing abnormal combustion such as diesel knocking and the like at the time of engine start by communicating the inside of a combustion injection pump chamber with the atmosphere at the time of stopping the engine, and dispersing away low boiling point fuel such as remaining DME(dimethyl ether) to the atmosphere.

A three way solenoid valve 14 interlocked with start and stop of an engine is arranged on the way of a connecting pipe 10 for connecting a fuel tank 1 an a fuel injection pump 2 to each other. The three way solenoid valve 14 is used, the fuel tank 1 and the fuel injection pump 2 are communicated with each other at the time of engine operation, the fuel tank 1 is closed at the time of stopping the engine, and a space between the fuel injection pump 2 and the three way solenoid valve 14 is communicated with the outside of a system. The three way solenoid valve 14 is switched at the time of stopping the engine, and it is stopped that fuel is forcibly supplied from the fuel tank 1 to the injection pump 2. Accordingly, DME fuel in the fuel tank 1 is sealed, and the DME in the fuel injection pump 2 and the fuel injection nozzle 3 is discharged to the atmosphere.