I have an 1984 70hp Evinrude outboard that runs great - just wont shut off when the ignition is in the off position. I have to choke it to get it to stop. The kill switch also does nothing. I took the controls apart and tried lifting the ground, the engine started fine but would not shut off. Not sure what to try next? Should the engine shut off when grounded, or when the ground is lifted? Is my power pack to blame? any suggestions welcome.