A method of boot strap starting a diesel having a plurality of cylinders comprises the steps of initiating cranking the diesel and responsive to cranking forcing exhaust valves for all cylinders open during compression strokes. Thereafter, responsive to the engine rotational speed signal exceeding a first threshold, an exhaust valve for one cylinder is allowed to open and close in synchronous with movement of a piston in the cylinder. Further responsive to engine rotational speed exceeding a second threshold higher than the first threshold, cranking is discontinued and the remaining exhaust valves are allowed to open and close in synchronous with movements of pistons in their respective cylinders.