2) Check the vacuum connection to the EGR valve
for obstructions.
3) Connect the pump between the EGR valve and
the carburetor or vacuum source. Start the engine
and run it at idle until it reaches operating
temperature (195°F approx.). Check for vacuum
at 3000 RPM; it should be 5" Hg minimum.
4) If no vacuum is available in step 3, check for it
between the EGR thermal vacuum switch (TVS) and
the carburetor. If the vacuum is available there,
replace the TVS.
5) If the vacuum supply between the EGR and the
carburetor is adequate, connect the pump to the
EGR valve inlet. Depress the valve diaphragm and
apply approximately 10" Hg vacuum to the EGR.
Release the diaphragm and record the time it takes
for the diaphragm to return to its seated position.
6) If it takes less than 20 seconds for the valve to
seat, replace the valve.
GM POSITIVE BACKPRESSURE EGR TEST
1) Follow steps 1 through 4 of the ported vacuum
and negative back-pressure EGR test.
2) Remove the EGR valve from the engine.
Connect the pump to the EGR vacuum inlet and
apply 10" Hg of vacuum. The valve should not
open. If it does, replace the valve.
3) Continue the test by keeping the vacuum applied
and shooting a low-pressure stream of air into the
valve’s exhaust inlet. The valve should now open.
If it does not, replace the valve.
11
EXHAUST GAS RECIRCULATION (EGR)
FIGURE 8: CHRYSLER VENTURI VACUUM-CONTROL EGR SYSTEM
To Starter Relay
Manifold Vacuum
To Ignition
Vacuum Amplifier
EGR Delay
Solenoid
EGR Valve
EGR Delay
Timer
CCEGR Temperature Valve
Coolant Control Engine Vacuum Switch
