Trap Door Test

1. With engine off, remove air cleaner cover and observe position of trap door. It should be closed.
2. Disconnect vacuum hose from intake manifold vacuum source and apply an external vacuum of 2-4 inches Hg. Trap door should open.
3. If door does not open, apply vacuum directly to vacuum motor on air cleaner intake duct. If door does not open, check for binding or distortion and adjust as necessary. Replace vacuum motor if door swings freely.
4. If door opens when vacuum is applied in step 3, inspect vacuum hose for obstructions, cracks and kinks. Correct as necessary and retest.
5. If vacuum hose is satisfactory, remove reverse delay valve, then join vacuum hoses and perform step 2. If door opens, replace reverse delay valve.