1970-73 All Models (Ported EGR Valve)
- Ensure engine is at normal operating temperature. Disconnect vacuum hose at EGR valve. Connect a hand-held vacuum pump to EGR valve. Start engine. Apply vacuum to EGR valve. If engine runs rough or stalls, and EGR valve holds vacuum, EGR valve is functioning properly.
- Connect a vacuum gauge to EGR hose. Increase engine speed to about 3000 RPM. If vacuum is shown on gauge, system is functioning properly.