Deceleration Fuel Cut-Off System: Description

The deceleration systems reduce HC emissions through the use of an air switching valve, coasting air valve, dashpot (Man. Trans. only), and a deceleration spark advance system consisting of an engine speed sensor and solenoid valve. The air switching valve cuts off fuel to by-pass holes and pilot outlet by supplying additional air to slow idle passage. The coasting air valve supplies additional air to the intake manifold. The deceleration spark advance system advances ignition timing, which is usually controlled by carburetor ported vacuum and engine speed.