Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Deceleration Fuel Cut-Off System: Operation
Deceleration system relay is activated only when coolant temperature is above 113°F (45°C), time relay is activated and engine speed exceeds 1400-1750 RPM. When throttle switch closes, system will operate until engine speed decreases below 1375F75 RPM.
During system operation, airflow is directed through by-pass hose and vacuum valve instead of passing the airflow sensor plate. Airflow sensor plate then closes which cuts off fuel supply to cylinders. See Fig 1 .
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.