haganwd

Hello, I had check engine light come on ('07 Tahoe), I had codes p0049/50, I then changed solinoid and gas cap with no change.
Took truck to dealer and after they smoke tested it they said "by the above TSB the filter assembly and solinoid needed to be moved to a different location because of excessive moisture exposure and that the new fuel cap I installed yesterday needed to be replaced". I asked where inside or under the hood, they answered no closer to the front of truck on the underside. I also stated I had replaced the fuel cap yesterday and they said they would replace the cap under warranty. Has anyone else had similar expirence? Does anyone have the above mentioned TSB? Thank you.

MDTAHOE

Here you go. Sorry I can not post the pictures .

Bulletin No.: 09-06-04-028

Date: June 16, 2009

Subject: Malfunction Indicator Lamp (MIL) Illuminated, DTCs P0442, P0446, P0455 or P0449 Set - Fuel Tank Hard to Fill - Moisture, Water, Corrosion at Evaporative Emissions (EVAP) Canister Vent Solenoid (CVS) Valve (Replace Conduit, Install New CVS
Valve and Revised Filter)

Models:
2007-2009 Cadillac Escalade, Escalade ESV, Escalade EXT
2007-2009 Chevrolet Avalanche, Suburban, Tahoe
2007-2009 GMC Yukon, Yukon XL, Yukon Denali, Yukon XL Denali

Condition

Some customers may comment that the fuel tank is hard to fill.

Some customers may also comment that the malfunction indicator lamp (MIL) is illuminated.

The technician may find DTCs P0442, P0446, P0455 or P0449 set as current or in history.

The technician may observe evidence of water intrusion at the evaporative emissions (EVAP) canister vent solenoid (CVS) valve.

Cause

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.

Correction

Note
If the revised filter is already installed on the vehicle, refer to the appropriate DTC procedures in SI.

1. Turn OFF the ignition, and all electrical components, including the scan tool if connected.
2. Remove the fuel fill cap.








3. Remove the fuel tank filler housing to body TORX(R) screws (1) and retainer (2).
4. Raise and support the vehicle at the appropriate height, in order to gain access to the spare tire assembly. Refer to Lifting and Jacking the Vehicle in SI.








5. Remove the spare tire and wheel assembly.








6. Disconnect the chassis wiring harness electrical connector (1) from the CVS valve.








Important
Clean the EVAP line connections and surrounding areas prior to disconnecting, in order to avoid possible EVAP system contamination.

7. Disconnect the CVS valve quick connect fitting (1) from the EVAP canister, and disconnect the fuel filler pipe EVAP line quick connect fitting (3) from the CVS valve. Refer to Plastic Collar Quick Connect Fitting Service in SI.








8. Disengage the retainer (1) securing the CVS valve to the bracket, and remove the CVS valve.








9. Remove the zip ties (1) as needed, and the CVS valve black conduit and mushroom cap (2).
10. Leave attached a 50 mm (2 in) piece of the CVS valve black conduit to the plastic collar quick connect fitting that was disconnected from the CVS valve.
11. Securely connect a 1.22 m (48 in) length of 19 mm (0.75 in) inside diameter heater hose to the 50 mm (2 in) piece of black conduit that is connected to the plastic collar quick connect fitting for the CVS valve.
12. Install and fully seat the revised CVS valve filter into the open end of the 1.22 m (48 in) heater hose that is attached to the 50 mm (2 in) piece of black conduit.

13. Lower the fuel tank filler pipe housing (3), and the fuel tank fill hose (4).








14. Add two holes to the fuel tank filler pipe housing, approximately 25 mm (1 in) apart as indicated in the illustration, in order to secure the heater hose, and CVS valve filter with a zip tie to the housing.








Note
Observe the proper orientation of the CVS valve filter (1) in the illustration.

15. Secure the CVS valve filter (1) and the CVS valve heater hose to the fuel tank filler pipe housing with a zip tie as indicated in the illustration. Position the zip tie so that sharp surfaces are not present within the fuel cap area of the housing.
16. Raise the fuel tank filler pipe housing, and the fuel tank fill hose back to the original position, and install the zip ties that were removed from their previous locations. Verify that kinks do not exist at any point in the heater hose.








17. Install the CVS valve and connect the electrical connector. Connect the CVS valve quick connect fitting (1) to the EVAP canister, and connect the fuel filler pipe EVAP line quick connect fitting (3) to the CVS valve. Refer to Plastic Collar Quick Connect Fitting Service in SI.
18. Install the spare tire and wheel assembly.
19. Lower the vehicle.








20. Install the fuel tank filler housing to body TORX(R) screws (1) and retainer (2).

Tighten
Tighten the screws to 2.3 Nm (20 lb in).

21. Install the fuel fill cap.
22. With a scan tool clear any DTCs that may be present
I can not post the pictures.

haganwd

Would replacing the CVS and not doing this conversion cause the check engine light to remain on?

Lucienne Offutt

Timely discussion - I was enlightened by the insight ! Does anyone know where my business would be able to get access to a blank VA 21-0845 example to fill out ?