An automatic speed-governing device which may govern the amount of deliveried oil from an ejector for a diesel engine (especially for a single-cylinder diesel engine in a motor vehicle) is composed of a centrifugal mass-type governor in which there is a spring for governing the additional amount of deliveried oil at starting, furthermore, there are an another spring to govern the idling rate of the engine and a spring to govern the operating mode at different speed of revolution. In the device, there is an assemblage which is able to keep the governor at such a position that makes the ejector at the top of output under the condition that the starting speed of revolution is greater than the idling rate and when the speed of revolution reaches the starting speed of revolution, especially in the case of idling operating mode, the governing action effected by the assemblage will stop. |