This system is only used on the 4A-F engines.

OPERATION

See Figure 1

The air suction (AS) system brings fresh, filtered air into the exhaust ports to reduce HC and CO emissions. On some applications, it also supplies the air necessary for the oxidizing reaction in the catalytic converter. The air suction system is different for the Federal models vs. the California models. Federal models are only equipped with an air reed, whereas the California models are equipped with a shut-off valve and air reed.



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Fig. Fig. 1: Air Suction (AS) system airflow-California shown, others similar

TESTING

Air Suction Reed Valve

See Figure 2

  1. Remove the air cleaner lid.
    2.  
  2. With the engine idling, check that a bubbling noise is heard from the AS valve inlet.
    3.  



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Fig. Fig. 2: Listen for a bubbling noise from the air suction reed valve inlet during idle

  1. Check that there is no air passage when air is blown hard into it, and when the air passage is sucked.
    2.  
  2. Reinstall the air cleaner cap.
    3.  

Air Suction Shut-Off Valve

This valve is only found on California models.

  1. Disconnect the vacuum hose from the shut-off valve and plug the hose end.
    2.  
  2. Remove the air cleaner lid.
    3.  
  3. Start the engine.
    4.  
  4. Reconnect the vacuum hose to the shut-off valve and check that a bubbling noise is heard from the AS valve inlet within 2-6 seconds.
    5.  
  5. Resinatll the air cleaner lid.
    6.