Hy Allen Lane, what usually causes a runaway is the injector fuel rack getting stuck in the full load governed speed position. The old racks were a two screw design, so that if even one injector was to stick, it would hold all the injectors in the same position. Newer racks had only one screw and a spring to replace the second screw, so even if a single injector stuck, the other injectors would still operate independent of the one that was stuck. The positioning of the fuel rack for "high idle" and full load governed speed is quite different, and unfortunately injectors tend to stick in full load position. Before attempting to start any engine which has been out of service for an extended time, make sure your fuel control system is functioning correctly, and is in the idle position, hope that helps.
