Exhaust Gas Recirculation: Testing and Inspection

1. Check the vacuum hoses for routing and installation.
2. Cold start and run the engine at idle speed.
3. Check to ensure that increasing engine rpm (idle to 2,500 rpm) does not cause the EGR valve to operate. If the EGR valve operates replace the thermo valve.
4. Warm up the engine until coolant temperature exceeds 85 to 95 degrees C (185 to 205 degrees F).
5. Check to ensure that when engine rpm is increased as described under step 3 that the EGR valve operates. If the EGR valve does not operate inspect the EGR control valve or the thermo valve.
6. Disconnect the green striped hose from the thermo valve.
7. Connect a vacuum pump to the thermo valve and apply vacuum. If no vacuum is present replace the thermo valve.
8. Remove vacuum pump from thermo valve and reconnect green stripe hose to thermo valve.
9. Disconnect the green stripe hose from the nipple of carburetor and connect a vacuum pump to the green stripe hose end.
10. While opening the sub EGR valve by pulling it by hand, apply -32 kPa (-9.8 in. Hg) vacuum with a vacuum pump.
11. If the idling speed becomes unstable the EGR valve is operating properly. If the idling speed remains unchanged the EGR valve is not operating and must be replaced.
12. Remove a vacuum pump from the green striped hose end and reconnect the green striped hose to the carburetor.
13. Disconnect the yellow striped hose from the EGR control valve.
14. Connect a vacuum pump to the nipple of EGR control valve.
15. While opening the sub EGR valve by pulling it by hand, apply -20 kPa (-5.9 in. Hg) vacuum with a vacuum pump.
16. If the idling speed becomes unstable, the EGR valve is operating properly. If the idling speed remains unchanged the valve is not operating. Replace the EGR valve.
17. Remove the vacuum pump from the EGR control valve and reconnect the yellow striped hose to the nipple of the EGR control valve.