Exhaust Gas Recirculation (EGR) System

Fig. 149 Testing EGR system:

1. Disconnect the vacuum hose (green stripe) from the carburetor throttle body and connect a hand vacuum pump to the vacuum hose, Fig. 149.
2. Start the engine and while it is cold (coolant temperature less than 45 degrees C or 113 degrees F) increase engine speed to 3,500 rpm and apply vacuum. Verify that vacuum leaks through the thermo valve.
3. Allow the engine to warm up (coolant temperature greater than 85 degrees C or 185 degrees F) and apply vacuum while the engine is at idle. Verify that vacuum leaks.
4. Increase engine speed to 3,500 rpm and apply vacuum. Verify that vacuum leaks until vacuum reaches approximately 11 kPa (3 in. Hg).