functions as the second electrode for the spark plug when an electrical circuit is completed between the central electrode 29 and the injector piece 10 39 acting as the second electrode a spark occurs radially across the annular gap or space 27 at edge 51 of the injector piece 10 39 as an improvement to the type of apparatus shown in my earlier u s pat no 2 990 653 fuel is supplied to the burner 10a by means of a fuel supply tube 20 which terminates within a circular hole 52 within face 38 of the injector piece 10 39 the fuel tube 20 opens to a slightly inclined smaller diameter fuel passage 21 which in turn feeds to a fine or small diameter inclined fuel supply passage 22 opening at port 22a within the end face 39 of the injector piece 10 39 adjacent the circular edge 51 defining the second electrode for the burner 10a thus a liquid fuel such as diesel oil is fed under pressure as indicated by arrow 53 into the combustion chamber interior at a region immediately in front of the termination point for bore 45 and the annular gap or space 27 between the first and second electrodes as a further important aspect of the present invention an oxygen enriched gas such as pure oxygen under pressure is fed to the annular gap or space 27 by means of an oxygen supply tube 23 which projects within a circular hole 54 within the injector.