Negative Back Pressure EGR Valve

1. Check valve signal tube orifice for obstructions, then connect a suitable vacuum gauge between valve and carburetor.
2. Bring engine to normal operating temperature and run at approximately 3000 RPM. Gauge should read approximately 5 inches Hg.
3. Depress valve diaphragm and place finger over source tube.
4. Release diaphragm and check seat for movement.
5. If valve takes less than 20 seconds to move to the seated position, replace the valve.
6. If the EGR valve functions properly, check the EGR-TVS.