Toyota Cressida/Corona/Crown/MarkII 1970-1982 Repair Guide

Deceleration Fuel Cut System

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This system cuts off part of the fuel in the slow circuit of the carburetor to prevent overheating and afterburning in the exhaust system.

TESTING



  1. Start the engine.
  2.  
  3. Check that the engine runs normally.
  4.  
  5. Pinch the vacuum hose to the vacuum switch.
  6.  
  7. Gradually increase the engine speed to 2,500 rpm. Check that the engine misfires between 2,000-2,500 rpm.
  8.  


WARNING
Perform this procedure quickly to prevent overheating of the catalytic converter.

  1. Release the pinched hose and see that the engine returns to normal operation.
  2.  
  3. Unplug the solenoid valve until the engine misfires or stalls.
  4.  
  5. Stop the engine and reconnect the wire.
  6.  

If the above tests are positive the procedure is complete. If not, inspect the solenoid valve and vacuum switch.

Fuel Solenoid
  1. Remove the solenoid.
  2.  
  3. Using two test wires, hook one to the positive and the other to the negative battery terminals.
  4.  
  5. Touch these two wires to the solenoid to determine if it clicks.
  6.  
  7. If it does click, it is operational. If not, discard it and replace it with a new one.
  8.  

Vacuum Switch
  1. Use a ohmmeter to check the continuity between the switch and the terminal body.
  2.  
  3. Start the engine.
  4.  
  5. Check that there is no continuity between the switch and the terminal body. If there is, replace the switch.
  6.  

 
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