PURPOSE: To prevent malfunction of a pressure-basis fuel trasnfer unit due to secondary waves, in an engine in which the second fuel is introduced into an injection nozzle via a pressure-basis fuel transfer unit based on the pulsating pressure of the first fuel, by interposing a throttle mechanism in a pressure conduit that introduces the said pulsating pressure into the pressure-basis fuel transfer unit.

CONSTITUTION: The captioned injection unit supplies alcohol 2, the first fuel, from a main fuel tank 1 to an injection pump 4 by a feed pump 3. And the fuel discharged from the injection pump 4 is supplied to No.1 injection passages 34 of injection nozzles 7 ( I to IV). The captioned injection unit also supplies kerosene 9, the second fuel, by an oil transfer pump 10 from an auxiliary fuel tank 8 to No.2 injection passages 35 of the injection nozzles 7 via pressure-basis fuel transfer units 12 ( I to IV). The said pressure-basis fuel transfer units 12 are provided to pressure-transfer the second fuel 9 to the injection nozzles 7 based on the pulsating pressure of the first fuel 2. In that case, a throttle mechanism 24 is interposed in a pressure conduit 23 that introduces the said pulsating pressure into the pressure-basis fuel transfer unit 12 so that the pressure wave form of the first fuel 2 is damped down before it is introduced into the transfer unit 12.