A governor sleeve is axially displaceable on a stationary governor shaft and has an inner space which is adjoined by the governor shaft and communicated with the inner chamber of a pump housing charged with fuel. The inner space varies in volume drawing thereinto and discharging therefrom fuel in response to axial displacement of the governor sleeve. There is provided valve and channel means which establishes restricted communication between the inner space and the inner chamber upon displacement of the governor sleeve in the direction to produce contraction of the inner space and substantially unrestricted communication between same upon displacement of the governor sleeve in the opposite direction to produce expansion of the inner chamber in order to prevent an acceleration jerk and smoky exhaust.