Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
This is usually caused by a faulty canister vent valve.here is some info to help you.
This condition may be caused by water spray that is generated by the rear wheels. The EVAP CVS valve draws fresh air into the EVAP system around a mushroom cap covered opening in the conduit that is mounted near the top of the fuel filler pipe. Under certain operating conditions, the moisture is ingested into the fresh air intake conduit opening, and is carried down though the conduit to the EVAP CVS valve causing corrosion in the CVS valve, and restrictions in the fresh air intake path, when the valve is in the closed position.
The water also collects in the CVS valve cyclonic filter in order to protect the EVAP canister. However if the capacity of the cyclonic filter is exceeded, this may result in water entering the EVAP canister and cause an additional restriction during refueling.
Important: Clean the EVAP line connections and surrounding areas prior to disconnecting, in order to avoid possible EVAP system contamination.
Note: Observe the proper orientation of the CVS valve filter (1) in the illustration.
Tighten Tighten the screws to 2.3 N·m (20 lb in).
Valve, EVAP EMIS CNSTR CONT
Filter, EVAP EMIS CNSTR VENT VLV
12368236 or Equivalent
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