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Normally Open Valve Without Vacuum Vent

  1. With engine at normal operating temperature, parking brake applied and transmission in "P" or "N", disconnect air supply line at valve outlet. Disconnect vacuum line at vacuum nipple.
  2. With engine at 1500 RPM, air should be heard and felt at valve outlet. Connect a direct vacuum line from any manifold vacuum source to vacuum nipple on valve. Air at outlet should be momentarily decreased or shut off.
  3. At same time, air pump supply air should be heard at silencer ports. If valve fails any test and air pump checks okay, replace valve. Reconnect vacuum lines.
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