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Colt, Colt Vista

  1. Check hoses for proper routing and condition. Cold start engine and run at idle. Watch EGR valve and be sure it does not operate as engine speed is increased to 2500 RPM. If it does, replace thermo valve.
  2. Warm engine until coolant is at 185-194°F (85-90°C). Increase engine speed to 2500 RPM. The EGR valve should now be operating. If not, check EGR and thermo valve and replace as necessary.
  3. Detach Green striped hose from thermo valve. Connect vacuum pump and apply vacuum. If no vacuum is available through thermo valve, valve is defective.
  4. Remove vacuum pump from thermo valve and reconnect Green stripe hose to thermo valve. Disconnect Green stripe hose from nipple of carburetor and connect a vacuum pump to Green stripe hose end.
  5. Apply 9.8 in Hg of vacuum while opening sub EGR valve by pulling it by hand. If idling speed becomes unstable the EGR valve is operating properly. If idling speed remains unchanged, valve is not operating properly. Replace EGR valve.
  6. Remove the vacuum pump from hose end. Reconnect hose to carburetor. Disconnect the Yellow stripe hose from the EGR control valve. Connect vacuum pump to the nipple of the EGR control valve.
  7. While opening the sub EGR valve by pulling it by hand, apply 5.9 in. Hg vacuum with a vacuum pump. If idling speed becomes unstable, EGR valve is operating properly. If idling speed remains unchanged, valve is not operating. Replace EGR valve.
  8. Remove a vacuum pump from EGR control valve and reconnect Yellow stripe hose to nipple of EGR control valve.
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