1982 Plymouth Sapporo Automatic TransFACTORY OEM SERVICE PROCEDURE

Deceleration Fuel Cut-Off System: Testing

  1. Run engine at idle. Disconnect solenoid valve connector to disable solenoid valve (manifold vacuum will act on air switching valve, causing valve to open). If idle drops excessively or engine stalls, air switching valve and solenoid valve are okay.
  2. If idle speed does not change, check vacuum passage for clogging and check condition of air switching valve or solenoid valve.
  3. With engine idling, battery voltage should be measured at solenoid connector. If voltage is not present, electrical wiring or engine speed sensor is defective.
  4. Increase speed to 1500 RPM. Check to ensure voltage is present at solenoid valve connector. If not, engine speed sensor is defective.
  5. Increase speed to 2500 RPM. Check to be sure no voltage is present at solenoid valve connector. If it is, engine speed sensor is defective.
Factory Service Tools

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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.

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