A governor sleeve is axially displaceable on a stationary governor shaft and has an inner space which is adjoined by the governor shaft and which communicates 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. According to the present invention, there is provided a helical groove which is formed in the outer cylindrical surface of the governor shaft or the inner cylindrical surface of the governor sleeve. Such groove effects a forced fuel conveying action of forcedly, though yieldingly, conveying fuel from the inner chamber to the inner space, which is effective in preventing an acceleration jerk and smoky exhaust upon rapid engine acceleration.