PURPOSE: To achieve both of the altitude compensation and the over-feed pressure compensation, by providing a suction pressure chamber for leading the suction pressure in the suction system and a standard pressure chamber for leading the standard pressurein in the suction pressure sensor for a suction pressure compensation device.

CONSTITUTION: A fuel injection pump 1 will feed the fuel through a distribution hole 8 of a pump plunger 3 into a delivery lead tube 10 and an internal combustion engine. The suction pressure sensor 50 is splitted through a diaphragm 42 into the suction pressure chamber 31 and the standard pressure chamber 40'. The fuel injection is determined by the dimension A of the right end face of a spill sleeve 11 and the right end face of a radial hole 12 of plunger 3. When the altitude of the car is increased to lower the atmospheric pressure, the differential pressure between the suction pressure chamber 31 and the standard pressure chamber 40' will decrease to move a slide pin 25 to the left while to move the spill sleeve 11 to the left. Consequently the fuel injection will decrease thus to prevent the increase of the exhaust black smoke. While when the supercharger will function to increase the pressure in the suction system, the fuel injection will increase. In such a manner the altitude compensation and the supercharge pressure compensation can be achieved.