1978 Models

During deceleration, when intake manifold vacuum exceeds a predetermined level, the fuel shut-off vacuum switch sends a signal to the anti-dieseling solenoid valve, shutting off fuel flow. When manifold vacuum is below this pre-determined level, the system is inoperative. The system is also controlled by the clutch switch and gear position switches, so that system can be deactivated, even though vacuum is above the pre-determined level.