EGR Functional Tests

4-156 ENGINE
1. Ensure vacuum hoses are properly routed and are not leaking.
2. With engine cold and idling, increase engine speed to 2500 RPM and ensure increase in speed does not cause secondary EGR valve to operate. If valve does operate, replace thermo valve.
3. Run engine until coolant temperature exceeds 149° F, then increase engine speed to 2500 RPM and ensure secondary valve operates. If valve does not operate, inspect EGR control valve or thermo valve.
4. Disconnect green striped hose from carburetor and connect a vacuum pump to hose.
5. Apply 6 inches Hg vacuum with a hand vacuum pump to sub EGR valve while pulling valve open by hand.
6. If idle speed becomes unstable, the secondary valve is operating properly. If idle speed does not change, the secondary EGR valve or thermo valve is not operating properly. Replace defective component.
7. Disconnect vacuum pump and reconnect hose to carburetor.
8. Disconnect yellow striped hose from carburetor and connect a vacuum pump to hose.
9. Apply 6 inches Hg vacuum with a hand vacuum pump to sub EGR valve while pulling valve open by hand.
10. If idle speed becomes unstable, the primary valve is operating properly. If idle speed does not change, the primary EGR valve or thermo valve is not operating properly. Replace defective component.