1980-84 All Models
- Ensure engine is at normal operating temperature. Install "T" fitting between vacuum port and EGR valve. Connect vacuum gauge to "T" fitting. Start engine and increase engine RPM. Vacuum should be present and EGR valve should open. Release throttle quickly. EGR valve should close. If vacuum is not present, clean vacuum port at intake manifold.
- Disconnect vacuum hose from EGR valve and plug hose. Apply vacuum to EGR valve. Engine should run rough or stall. If EGR valve functions as described, system is functioning properly.