Service Procedure
The following procedures provides information for diagnosing whether it is necessary to replace the fuel tank pressure sensor only, or the complete fuel tank assembly and evaporative (EVAP) emission canister. Read the entire service procedure before beginning any work.1. Connect a Tech 2 to the vehicle's diagnostic link connector (DLC) and inspect for diagnostic trouble code (DTC) P0440 or P0446.
^ If neither code is stored, the fuel tank pressure sensor must be replaced. Disconnect the Tech 2 and proceed to the section below titled, "Fuel Tank Pressure Sensor Replacement."
^ If one or both of the codes are stored, additional diagnosis must be performed; proceed to the next step.
2. Raise the vehicle on a suitable hoist and support as necessary.
3. Disconnect the hoses from the vapor canister. For additional information, refer to the "Evaporative (EVAP) Emission Canister Replacement" section in the appropriate Service Manual or SI.
4. Remove the three nuts that attach the vapor canister to the vehicle and remove the canister and bracket.
5. Tip the canister upside down (hose fitting facing downwards) and inspect for any fuel leakage.
^ If ANY AMOUNT of fuel comes out, the complete fuel tank assembly and EVAP canister must be replaced. Do not install the new canister until instructed to do so in the service procedure. Proceed to the section below titled "Complete Fuel Tank Assembly and EVAP Emission Canister Replacement."
^ If no fuel comes out of the canister, then only the fuel pressure sensor needs to be replaced. Reinstall the canister and connect the hoses. Tighten the nuts to 6 Nm (53 lb-in). Lower the vehicle and proceed to the section below titled "Fuel Tank Pressure Sensor Replacement."
Fuel Tank Pressure Sensor Replacement
This procedure should be used if ONLY the fuel tank pressure sensor requires replacement.
1. Open the rear compartment (trunk) and reposition the floor carpeting as necessary to access the fuel tank sending unit access panel.
2. Remove the bolts that attach the access panel to the floor.
3. Remove the access panel.
Important
Do not remove the sending unit from the fuel tank in the next steps.
4. Locate the fuel tank pressure sensor on top of the sending unit and disconnect the electrical connector.
5. Using a twisting motion, carefully pull up on the fuel tank pressure sensor to unplug it from the sending unit.
6. Position the new fuel tank pressure sensor to the hole in the sending unit and press it firmly into place.
7. Connect the electrical connector to the fuel tank pressure sensor.
8. Position the access panel to the floor pan opening and install the attaching bolts.
Tighten
Tighten to 2 Nm (18 lb-in).
9. Reposition the floor carpeting and close the rear compartment lid.
10. Install the GM Recall Identification Label.
Complete Fuel Tank Assembly and EVAP Emission Canister Replacement
This procedure should be used only if the easier diagnosis indicated that the complete fuel tank and EVAP emission canister requires replacement. If only the fuel tank pressure sensor requires replacement, do NOT use this procedure. Use the procedure titled, "Fuel Tank Pressure Sensor Replacement."
Tools Required
J 34730-1A Fuel Pressure Gauge
Important
The replacement fuel tanks listed in the Parts Information section come complete with the sending unit/fuel pump, hoses, pressure sensor, etc.
Important
This procedure takes into consideration that the EVAP emission canister was removed during the diagnosis; however, it does include information on installation of the new EVAP emission canister.
1. Lower the vehicle.
2. Open the hood.
3. Remove the fuel injector sight shield (engine cover).
^ On V6 supercharged engines, remove the nut and oil filter cap.
^ On V8 engines, remove the two nuts.
4. Remove the rear seat cushion and disconnect the negative battery cable.
5. Remove the fuel cap.
Caution
Gasoline and gasoline vapors are highly flammable. A fire could occur if an ignition source is present. Never drain or store gasoline or diesel fuel in an open container, due to the possibility of fire or explosion. Have a dry chemical (Class B) fire extinguisher nearby.
Caution
Relieve the fuel system pressure before servicing fuel system components in order to reduce the risk of fire and personal injury.
After relieving the system pressure, a small amount of fuel may be released when servicing the fuel lines or connections. In order to reduce the chance of personal injury, cover the regulator and the fuel line fittings with a shop towel before disconnecting. This will catch any fuel thank may leak out. Place the towel in an approved container when the disconnection is complete.
6. Remove the cap and connect the J 34730-1A, Fuel Pressure Gage, to the fuel pressure port and relieve the fuel pressure. For additional information, refer to "Fuel Pressure Relief Procedure" in the appropriate Service Manual or in SI.
7. Reinstall the cap on the fuel pressure port and install the engine cover and oil fill cap (V6 models only).
Tighten
^ Tighten the V8 engine cover nuts to 3 Nm (27 lb-in).
^ Tighten the V6 supercharged engine cover nuts to 2 Nm (18 lb-in).
8. Drain the fuel tank. For additional information, refer to "Fuel Tank Draining Procedure" in the appropriate Service Manual or in SI.
Caution
To avoid any vehicle damage, serious personal injury, or death when major components are removed from the vehicle and the vehicle is supported by a hoist, support the vehicle with jack stands at the opposite end from which the components are being removed.
9. Raise the vehicle on a suitable lift and support as necessary.
10. Remove the rear wheels.
11. Release the retainers and remove the panel that covers the opening between the fuel fill pipe and the left rear wheelhouse.
12. Loosen the clamp and disconnect the fuel fill pipe from the hose that is attached at the fuel tank.
13. Remove the oxygen sensor from the exhaust pipe. When unscrewing the sensor from the pipe, allow the wiring on the sensor to "wind-up" inside of the heat shield.
14. Suitably support the exhaust system.
15. Remove the four nuts that attach the exhaust manifold flange to the catalytic converter. For additional information, refer to the "Exhaust System Replacement" procedure in the appropriate Service Manual or in SI.
16. Remove the two bolts that attach the center exhaust hangers to the rear suspension support brackets.
17. Remove the two nuts that attach the rear exhaust hangers to the rear exhaust hanger brackets.
18. With the aid of an assistant, remove the exhaust system from the vehicle.
19. Disconnect the automatic level control link from the LEFT lower control arm, and if equipped, from the RIGHT lower control arm.
20. On models equipped with continuous variable road sensing suspension, disconnect the 2-way electrical connector at each lower control arm. Release the three retainers that attach the harness to the lower control arms.
21. Disconnect the rear wheel speed sensor electrical connectors from the hub assemblies.
22. If equipped, remove the bolt that attaches the wiring harness and parking brake cable to both lower control arms.
Notice
Do not hang the caliper from the hose in the next step.
23. Remove the bolts that attach both rear brake calipers and remove the calipers.
Support the caliper to the body as necessary. Do not disconnect the brake hose or hang the caliper from the hose. For additional information, refer to the "Rear Brake Caliper Replacement" procedure in the appropriate Service Manual or in SI.
24. Remove the bolts that attach the bottom of each rear shock absorber to the lower control arms.
25. Disconnect the 7-way electrical connector and separate the wiring harness from the body at the rear of the right wheelhouse.
26. Using a transmission jack or equivalent, support the rear support or cradle assembly. For additional information, refer to the "Support Replacement" procedure in the appropriate Service Manual or in SI.
27. Remove the four bolts [(3) 15 mm hex head and (1) 18 mm hex head] and plate that attach the RIGHT front corner of the rear support to the body. DO NOT remove the equivalent bolts on the left side.
28. Remove the two bolts that attach the rear of the support to the body.
29. Carefully lower the rear support assembly with the transmission jack.
30. Remove the right rear cool spring.
31. Disconnect the fuel line connections at the fuel filter. For additional information, refer to the "Quick Connection Fitting(s) Service" procedure in the appropriate Service Manual or in SI.
32. Remove the two 13 mm hex head bolts that attach the fuel tank straps to the rear of the vehicle and lower the straps.
33. With the aid of an assistant, remove the fuel tank out the right side of the vehicle while guiding the fuel lines and fill hose.
Important
Note the alignment of the fuel fill hose on the old fuel tank before removing it in the next step.
34. Loosen the clamp that attaches the fuel fill hose to the fuel tank and remove the hose.
35. Install and align the hose on the new fuel tank.
Tighten
Tighten the clamp to 3.5 Nm (31 lb-in).
36. With the aid of an assistant guiding the vent pipe into the fuel fill hose and routing and fuel lines to the body, install the new fuel tank to the vehicle.
37. Position the fuel tank straps and install the bolts.
Tighten
Tighten to 42 Nm (31 lb-ft).
38. Remove the bolt that attaches the bracket to the vapor canister and separate the bracket.
39. Install the bracket to the NEW vapor canister and install the bolt.
Tighten
Tighten to 6 Nm (53 lb-ft).
40. Install the new vapor canister and bracket to the body and install the three nuts.
Tighten
Tighten to 6 Nm (53 lb-ft).
41. Connect the hoses to the vapor canister.
42. Connect the fuel lines at the fuel filter.
43. Position the right rear coil spring and raise the rear support assembly to the body.
44. Install the two rear bolts that attach the rear support assembly to the body.
45. Position the plate and install the four bolts [(3) 15 mm hex head and (1) 18 mm hex head] at the right front comer of the support assembly.
Tighten
^ Tighten the three 15 mm hex head bolts that attach the plate to the body to 86 Nm (63 lb-ft).
^ Tighten the one 18 mm hex head bolt to 191 Nm (141 lb-ft).
^ Tighten the two support bolts to 191 Nm (141 lb-ft).
46. Remove the transmission jack or equivalent.
47. Connect the 7-way electrical connector and attach the harness to the body at the rear of the right wheelhouse.
48. Position the rear shock absorber lower mount to the lower control arms. Install the bolts.
Tighten
Tighten to 24 Nm (18 lb-ft).
49. Install the brake calipers and mounting bolts (pins).
Tighten
Tighten to 27 Nm (20 lb-ft).
50. If equipped, position the harness and park brake cable to the lower controls arms and install the bolt.
Tighten
Tighten to 24 Nm (18 lb-ft).
51. Connect both rear wheel speed sensor electrical connectors.
52. On models equipped with continuous variable road sensing suspension, connect the 2-way electrical connector at each lower control arm. Secure the harness to the lower control arms with the three retainers.
53. If equipped, connect the automatic level control links to the lower controls arms.
54. With the aid of an assistant, install the exhaust system. Install the fasteners.
Tighten
^ Tighten the rear exhaust hanger nuts to 30 Nm (22 lb-ft).
^ Tighten the four nuts at the catalytic converter to 25 Nm (18 lb-ft).
^ Tighten the center exhaust hanger bolts to 30 Nm (22 lb-ft).
55. With the wiring harness still in "wind-up", install the oxygen sensor in the exhaust pipe. As you install the sensor, the wiring harness will begin to unwind.
Tighten
Tighten the sensor to 41 Nm (30 lb-ft).
56. Connect the fuel fill pipe to the hose on the fuel tank.
Tighten
Tighten the clamp to 3.5 Nm (31 lb-ft).
57. Position and engage the retainers on the panel that covers the opening between the fuel fill pipe and the left rear wheelhouse.
58. Install the rear wheels and nuts.
Tighten
Tighten to 140 Nm (103 lb-ft).
59. Lower the vehicle.
60. Refill the fuel tank with the fuel removed earlier and install the fuel cap.
61. Connect the negative battery cable.
62. Reinstall the rear seat cushion.
63. Using the Tech 2, clear the stored codes from memory.
64. Install the GM Recall Identification Label.