Automatic pollution control is one benefit of using the cylinder pressure to develop the injection pressure. In particular, if the engine cylinder develops a fault, such as a broken piston ring, leading to a drop in pressure in the cylinder, the pressure drop will immediately prevent or at least reduce the charge of fuel that the injector will introduce into that cylinder. Thus the engine will exhaust less unburnt fuel compared to an engine where a full charge continues to be injected into a faulty cylinder. This compensation also occurs in the case of normal wear of components so that pollution reduction and wear compensation results.

Another benefit of the injector is that it provides automatic timing adjustment. In particular, as an associated engine increases in running speed, ideally, the commencement of injection should be advanced in the operating cycle since the fuel needs a predetermined minimum time to burn completely regardless of the speed of the engine. With the injector of the present invention, as the engine piston commences the compression cycle, there is a faster build up of pressure in the cylinder at higher engine speeds since the heat is not escaping as quickly from the engine as at lower speeds. This more rapid increase in pressure will automatically advance the commencement of injection to earlier points in the engine cycle. This advancement can be in excess of 15.degree. from initial setting to the point of injection at maximum engine speed.