To surely drive a system in both of opening and closing directions and to operate the system, regardless of injection pressure, by connecting two diaphragm chambers with pressure from an engine crank case and connecting one of the diaphragm chambers with crank case pressure via a flow limiting means.

A fuel injection device 22 is constituted of a suction port 38 connected with internal pressure of a crank case 18 an accumulator 34 having an exit 40, a valve 42 opening and closing the exit 40 of the accumulator 34, a diaphragm constituted of two diaphragm pressure chambers 48, 50 which are formed in opposite sides and are connected with the crank case 18, a valve assembly 36 and a housing. A flow limiting means 50 is provided on an outside chamber 50 and damps and averages pressure within the outside chamber 50 as compared with crank case pressure. A fuel measuring system 20 feeds fuel to a channel 60 and continuously, fuel is mixed with pressure pulse of air from the accumulator 34 and is injected to a combustion chamber 26.