Bronco L6-300 4.9L VIN Y 1-bbl (1983)
Air Injection Bypass Valve: Testing and Inspection
Normally Closed
1.
Disconnect air supply hose at valve outlet, then remove vacuum line and check if vacuum is present at vacuum nipple.
2.
Remove any restrictors or delay valves in vacuum line. Before proceeding to step 3, ensure vacuum is present at vacuum nipple.
3.
Reconnect vacuum line to nipple, then accelerate engine to 1500 RPM.
4.
Air pump supply should be present at air bypass valve outlet. Disconnect vacuum line, air at outlet should stop and air pump supply air should be
present at silencer port.
5.
If above step proves incorrect, check air pump, then bypass valve.
Normally Open With Vacuum Vents
1.
Disconnect air pump supply line at outlet, then vacuum lines from vacuum nipple and vacuum vent.
2.
Accelerate engine to 1500 RPM, air pump supply air should be present at outlet.
3.
Using suitable vacuum hose, connect vacuum nipple to intake manifold vacuum. No air should be present at valve outlet, all air should bypass
through silencer ports.
4.
Using the same vacuum hose as above step, cap vacuum vent and accelerate engine to 2000 RPM. Air pump supply air should be interrupted when
throttle is released.
5.
If above steps prove incorrect, check air pump, then bypass valve.
Normally Open Without Vacuum Vent
1.
Disconnect air supply line at valve outlet, then vacuum line at vacuum nipple.
2.
Accelerate engine to 1500 RPM, air pump supply air should be present at outlet.
3.
Using suitable vacuum hose, connect vacuum nipple to intake manifold vacuum. Air at outlet should decrease or shut off.
4.
Air pump supply air should be present at silencer ports.
5.
If above steps prove incorrect, check air pump, then bypass valve.
