Product Safety - Compressed Natural Gas (CNG) Fuel Line Leak

General Motors has decided that a defect, which relates to motor vehicle safety, exists in certain 2002 model year Chevrolet Silverado and GMC Sierra pickup trucks equipped with a bi-fuel CNG (KL6) or dedicated CNG (KL8) fuel system. Some of these vehicles have a condition where the throttle cable may contact and wear through the CNG fuel line, resulting in a fuel leak. If a leak were to occur, the Service Engine Soon light may illuminate and a strong odor of natural gas may be detected from inside of the vehicle, possibly accompanied by a hissing noise. If the natural gas were accidentally ignited, serious injury could result. A dedicated CNG truck will lose power and eventually stall while a bi-fuel truck will switch to gasoline operation. If the vehicle stalls or switches to gasoline operation, a lock-off valve would close, interrupting the supply of CNG and stop the leak.

Dealers are to secure the throttle cable to eliminate the possibility of contact with the CNG fuel line. The CNG fuel line, throttle cable, and cruise control cable are also to be inspected and replaced if necessary.

Involved are certain 2002 model year Chevrolet Silverado and GMC Sierra pickup trucks equipped with a bi-fuel (KL6) or natural gas (KL8) fuel system and built within these VIN breakpoints:

Important: Dealers should confirm vehicle eligibility through GMVIS (GM Vehicle Inquiry System) before beginning recall repairs. [Not all vehicles within the above breakpoints may be involved.]

Computer listings containing the complete Vehicle Identification Number, customer name and address data of involved vehicles have been prepared, and are being furnished to involved dealers. The customer name and address data will enable dealers to follow up with customers involved in this recall. Any dealer not receiving a computer listing has no involved vehicles currently assigned.

These dealer listings may contain customer names and addresses obtained from Motor Vehicle Registration Records. The use of such motor vehicle registration data for any other purpose is a violation of law in several states/provinces/countries. Accordingly, you are urged to limit the use of this listing to the follow-up necessary to complete this recall.

Preshipment - Quantum Technologies will send an initial supply of parts to involved dealers at no charge. Additional parts, if required, are to be obtained from Quantum Technologies by completing the Part Request Form contained in this bulletin (page 9) and faxing it to 949-930-3401. Do not order parts from GMSPO.

The following information provides direction for inspecting for contact (rubbing) between the compressed natural gas (CNG) fuel line and the accelerator cable and if equipped, the cruise control cable.

If the inspection below reveals that the CNG fuel line, accelerator cable, or cruise control cable are in contact (rubbing) and that significant damage to either has occurred, it will be necessary to replace them. All parts required for this recall are to be obtained from Quantum Technologies. Simply complete the information needed on the form found on page of this bulletin and fax it to them. DO NOT attempt to obtain parts from GMSPO.

If you have any questions regarding the inspection, call Quantum Technologies at 1-800-816-8691 between 8:00 a.m. and 5:00 p.m. PST (Pacific Standard Time) or 11:00 a.m. to 8:00 p.m. EST (Eastern Standard Time). DO NOT call GM Technical Assistance Center (TAC) for questions on this recall.

Inspection Procedure

Important: The following two illustrations show the different types of accelerator cable routings that you may find. The first one shows a vehicle with the accelerator cable routed BELOW the cruise control cable. This illustration should also be used for vehicles that do NOT have cruise control. The second illustration shows the accelerator cable routed OVER the cruise control cable.

Open the hood and determine which illustration matches your vehicle. Inspect for contact (5) between the CNG fuel line (4) and the accelerator cable (3), and between the cruise control cable (2) and the fuel line (4).

CNG Fuel Line Replacement (If Necessary)

For additional information and illustrations on replacing the fuel line from the union to the low pressure lock-off (LPL), refer to the appropriate Service Manual or SI (document ID 786464).

1. Connect a Tech 2 to the vehicle’s diagnostic link connector (DLC) and establish communications with the alternative fuels ECM.
2. Start the engine and allow it to idle.
3. Ensure that the engine is operating on CNG by observing that the fuel indictor lamp (FIL) is OFF and that both the AFO signal and the AFO signal command displays (Engine Data-Alt. Fuels) on the Tech 2 indicating that the AFECM is in command of engine fueling.
4. Proceed to Special Functions displays on the Tech 2.
5. While the engine is idling on CNG, command the high pressure lock-off (HPL) to OFF and then scroll up on the Tech 2 screen so that the fuel tank pressure sensor can be observed.
6. With the engine still idling and the HPL commanded OFF, the fuel tank pressure sensor should begin to decrease.

•	On vehicles with "dedicated" CNG systems, the engine will stall after a short time.

•	On vehicles with "bi-fuel" CNG systems, a switchover to gasoline will occur.

7. When the engine stalls (dedicated CNG systems) or switches over to gasoline (bi-fuel systems), turn the ignition switch to the OFF position and disconnect the Tech 2. If the engine does not stall (dedicated CNG systems) or switch to gasoline (bi-fuel systems) after a few minutes, this may indicate a problem with the high pressure lock-off (HPL) or the fuel system may have been altered. If present, this condition MUST be addressed before continuing with this procedure.
8. Remove the CNG 20-amp fuse from the underhood electrical center.
9. Disconnect both negative battery cables.

Caution: When relieving the CNG fuel system pressure, take the following precautions in order to prevent fire and personal injury:

•	Vent the CNG fuel system in a well ventilated work area.

•	Keep sparks, flames, and smoking material away from the area.

•	Wear the appropriate hearing protection during the venting procedure. A sudden pressure loss from an uncontrolled gas leak can cause hearing damage.

10. Slowly loosen the fuel line fitting at the low pressure lock-off (LPL) inlet port several turns. Fuel pressure should vent from the line for a few seconds.
11. Raise the vehicle on a suitable hoist and support as necessary.
12. Disconnect the LPL fuel line from the center fuel line at the bracket.
13. Release the fuel line from the retainers:

•	On vehicles with "dedicated CNG systems", release the fuel line from the retaining clips that attach it to the transmission. Also release the electrical connector (if equipped) from the fuel line.

•	On vehicles with "bi-fuel CNG systems", release the fuel line from the clips that attach it to the other regular (gasoline) fuel lines.

14. From underneath the vehicle, remove the CNG fuel line.

Important: Leave the protective shipping caps on the new fuel line to prevent dirt and other material from getting inside during installation.

15. From underneath the vehicle, route the new CNG fuel line up to the LPL on the engine.
16. Install the new CNG fuel line to the retainers or clip. If equipped, attach the electrical connector.

Caution: Natural gas is stored under high pressure. If a leak occurs, the high pressure could cause a personal injury. In order to prevent CNG fuel leaks, always replace the CNG fuel system O-rings during service.

17. Remove the protective shipping cap and lubricate the new O-ring (supplied with new fuel line) with petroleum jelly. Connect the new CNG fuel line to the center fuel line at the bracket.

Tighten
Tighten to 37 N·m(27 lb ft).

18. Lower the vehicle.
19. Remove the protective shipping cap and lubricate the new O-ring with petroleum jelly. Connect the new CNG fuel line to the LPL.

Tighten
Tighten to 37 N·m(27 lb ft).

20. Connect the negative battery cables.
21. Install the CNG 20-amp fuse in the underhood electrical center.
22. Start the engine and check for leaks using the J-45878 (combustible gas detector) or equivalent liquid leak detector.
23. If cables require replacement as indicated in the Inspection Procedure, refer to the appropriate section in this bulletin.
24. If no cables require replacement, refer to the section titled, "Isolator Kit Installation."

Accelerator Cable Replacement (If Necessary)

For additional information and illustrations see the appropriate Service Manual or SI (document ID 663399).

1. Remove the engine sight shield cover.
2. Disconnect the accelerator cable from the throttle body lever.
3. Disconnect the accelerator cable from the cable bracket on the intake manifold.
4. Remove the three bolts attaching the engine sight shield retainer to the intake manifold.
5. Unclip the accelerator cable from the retainer.
6. From underneath the instrument panel (IP), disconnect the accelerator cable from the accelerator pedal lever.
7. Squeeze the accelerator cable cover tangs and push the cable through the hole in the dash panel sheet metal.
8. Install the new accelerator cable through the hole in the dash panel sheet metal and snap the accelerator cable cover tangs into place.
9. Connect the accelerator cable to the accelerator pedal lever.
10. Install the engine sight shield cover retainer on the intake manifold.

Tighten
Tighten the bolts to 5 N·m(44 lb in).

11. Connect the accelerator cable to the throttle body lever.
12. Slide the accelerator cable into the slot in the cable bracket on the intake manifold and snap the locking tab into position.
13. Clip the accelerator cable to the engine sight shield retainer.
14. Install the engine sight shield cover and bolt.

Tighten
Tighten to 10 N·m(89 lb in).

15. If additional lines/cables require replacement as indicated in the Inspection Procedure, refer to the appropriate section in this bulletin.
16. If no additional lines/cables require replacement, refer to the section titled, "Isolator Kit Installation."

Cruise Control Cable Replacement (If Necessary)

For additional information and illustrations see the appropriate Service Manual or SI (document ID 787443).

1. Remove the engine sight shield cover.
2. Disconnect the cruise control cable from the throttle body lever.
3. Disconnect the cruise control cable from the cable bracket on the intake manifold.
4. Remove the three bolts attaching the engine sight shield retainer to the intake manifold.
5. Unclip the cruise control cable from the retainer.
6. Remove the four bolts and remove the upper left fender brace.
7. Disconnect the electrical connector from the cruise control module.
8. Remove the three nuts attaching the cruise control module to the cowl.
9. While depressing the two retaining tabs at the same time, remove the cruise control cable from the module.
10. Disconnect the cruise control cable from the fitting on the ribbon in the module.
11. Attach the new cruise control cable to the fitting on the ribbon in the module.
12. Pull the cruise control cable until the cable is taut.

Important: Use care not to twist the ribbon in the next steps. If the ribbon gets twisted, turn the engine-end fitting on the other end of the cruise control cable as needed in order to straighten it. Ensure that the ribbon is flat and vertical.

13. Slide the cruise control cable conduit over the ribbon and install the tangs into the cruise control module housing. Ensure that the tangs snap securely into place.
14. Install the cruise control module to the cowl and install the three attaching nuts.

Tighten
Tighten to 9 N·m(80 lb in).

15. Install the upper fender brace to the cowl and fender and install the four attaching bolts.

Tighten
Tighten to 9 N·m(80 lb in).

16. Install the engine sight shield retainer to the intake manifold and install the three bolts.

Tighten
Tighten to 5 N·m(44 lb in).

17. Route the cruise control cable over the top of the accelerator cable.
18. Connect the cruise control cable to the throttle body lever.
19. Slide the cruise control cable into the slot in the cable bracket on the intake manifold and snap the locking tab into position.
20. Clip the cruise control cable to the engine sight shield retainer.
21. Install the engine sight shield cover and bolt.

Tighten
Tighten to 10 N·m(89 lb in).

22. If additional lines/cables require replacement as indicated in the Inspection Procedure, refer to the appropriate section in this bulletin.
23. If no additional lines/cables require replacement, refer to the section titled, "Isolator Kit Installation."

Isolator Kit Installation

Important: The illustration below shows the cables that may be involved; however, on some vehicles the cruise control cable may be routed over the accelerator cable.




1. Open up the slit in the shortest of the three pieces of protective sheathing and install it on the CNG fuel line (4) as shown. Install one of the two remaining pieces on the accelerator cable (5) and the last piece on the cruise control cable (2) as shown (if equipped).

Important: In the next step install the head (locking feature) of the plastic support strap so that the "round hole" on the locking feature faces the sheet metal.

2. Screw the LARGE head of the plastic strap onto the metal stud (1) on the plenum sheet metal that has the ground wires already attached. When properly installed, the round hole in the locking feature of the LARGE head on the strap will be facing the plenum sheet metal and the "triangle" shaped opening on the opposite side will be facing toward the front of the vehicle.
3. Create a LARGE loop (6) with the strap by inserting the end of the plastic strap into the locking feature. Only allow the strap to lock into place by three or four clicks (ratchets). When the loop is complete there should NOT be any cables going through it.
4. Loop the other plastic strap (3) around the accelerator cable/sheathing, the cruise control cable if equipped, and through the first loop. Lock the strap into place by three or four clicks (ratchets). At this point, the two straps should be connected together in what looks like a "figure 8", with the cable(s) in the lower loop.
5. Slowly close the loop (pull it tighter) in the lower smaller strap until the two straps together are supporting the cable at least 13 mm (1/2 in) above the CNG fuel line. If either cable is still contacting the fuel line or is less than 13 mm (1/2 in) away and the lower strap loop cannot be made any shorter, then slowly begin to close the UPPER strap loop until the required clearance is achieved.
6. Install the GM Recall Identification Label.

Place a Recall Identification Label on each vehicle corrected in accordance with the instructions outlined in this Product Recall Bulletin. Each label provides a space to include the recall number and the five-digit dealer code of the dealer performing the recall service. This information may be inserted with a typewriter or a ballpoint pen.

Put the Recall Identification Label on a clean and dry surface of the radiator core support in an area that will be visible to people servicing the vehicle.

For US - When installing the Recall Identification Label, be sure to pull the tab to allow adhesion of the clear protective covering. Additional Recall Identification Labels can be obtained from Dealer Support Materials by either ordering on the web from DWD Store, gm-dealerworld.com, or calling 1-866-700-0001 (Monday-Friday, 8:00 a.m. to 5:00 p.m. EST). Request Item Number S-1015 when ordering.

The General Motors Courtesy Transportation program is intended to minimize customer inconvenience when a vehicle requires a repair that is covered by the New Vehicle Limited Warranty. The availability of courtesy transportation to customers whose vehicles are within the warranty coverage period and involved in a product recall is very important in maintaining customer satisfaction. Dealers are to ensure that these customers understand that shuttle service or some other form of courtesy transportation is available and will be provided at no charge. Dealers should refer to the General Motors Service Policies and Procedures Manual for Courtesy Transportation guidelines.

Submit a Product Recall Claim with the information indicated below:

Refer to the General Motors WINS Claims Processing Manual for details on Product Recall Claim Submission.

Customers will be notified of this recall on their vehicles by General Motors (see copy of customer letter included with this bulletin).

The US National Traffic and Motor Vehicle Safety Act provides that each vehicle which is subject to a recall of this type must be adequately repaired within a reasonable time after the customer has tendered it for repair. A failure to repair within sixty days after tender of a vehicle is prima facie evidence of failure to repair within a reasonable time. If the condition is not adequately repaired within a reasonable time, the customer may be entitled to an identical or reasonably equivalent vehicle at no charge or to a refund of the purchase price less a reasonable allowance for depreciation. To avoid having to provide these burdensome remedies, every effort must be made to promptly schedule an appointment with each customer and to repair their vehicle as soon as possible. In the recall notification letters, customers are told how to contact the US National Highway Traffic Safety Administration if the recall is not completed within a reasonable time.

All unsold new vehicles in dealers' possession and subject to this recall MUST be held and inspected/repaired per the service procedure of this recall bulletin BEFORE customers take possession of these vehicles.

Dealers are to service all vehicles subject to this recall at no charge to customers, regardless of mileage, age of vehicle, or ownership, from this time forward.

Customers who have recently purchased vehicles sold from your vehicle inventory, and for which there is no customer information indicated on the dealer listing, are to be contacted by the dealer. Arrangements are to be made to make the required correction according to the instructions contained in this bulletin. This could be done by mailing to such customers a copy of the customer letter accompanying this bulletin. Recall follow-up cards should not be used for this purpose, since the customer may not as yet have received the notification letter.

In summary, whenever a vehicle subject to this recall enters your vehicle inventory, or is in your dealership for service in the future, please take the steps necessary to be sure the recall correction has been made before selling or releasing the vehicle.

Dear General Motors Customer:

This notice is sent to you in accordance with the requirements of the National Traffic and Motor Vehicle Safety Act. Federal regulation requires that any vehicle lessor receiving this recall notice must forward a copy of this notice to the lessee within ten days.

General Motors has decided that a defect, which relates to motor vehicle safety, exists in certain 2002 model year Chevrolet Silverado and GMC Sierra pickup trucks equipped with a bi-fuel compressed natural gas (CNG) or dedicated CNG fuel system. Some of these vehicles have a condition where the throttle cable may contact and wear through the CNG fuel line, resulting in a fuel leak. If a leak were to occur, the Service Engine Soon light may illuminate and a strong odor of natural gas may be detected from inside of the vehicle, possibly accompanied by a hissing noise. If the natural gas were accidentally ignited, serious injury could result. A dedicated CNG truck will lose power and eventually stall while a bi-fuel truck will switch to gasoline operation. If the vehicle stalls or switches to gasoline operation, a lock-off valve would close, interrupting the supply of CNG and stop the leak.

Your GM Dealer will secure the throttle cable and eliminate the possibility of contact with the CNG fuel line. The CNG fuel line, throttle cable, and the cruise control cable will also be inspected and replaced if necessary. This service will be performed for you at no charge .

It will take approximately 15 minutes to secure the throttle cable. If the fuel line, throttle cable, and/or cruise control cable requires replacement, an additional 15 to 40 minutes will be required. However, due to service scheduling requirements, your dealer may need your vehicle for a longer period of time.

To limit any possible inconvenience, we recommend that you contact your GM dealer as soon as possible to schedule an appointment for this repair. By scheduling an appointment, your dealer can ensure that the necessary parts will be available on your scheduled appointment date. Should your dealer be unable to schedule a service date within a reasonable time, you should contact the appropriate Customer Assistance Center at the listed number below:

If, after contacting the appropriate customer assistance center, you are still not satisfied that we have done our best to remedy this condition without charge and within a reasonable time, you may wish to write the Administrator, National Highway Traffic Safety Administration, 400 Seventh Street SW, Washington, DC 20590 or call 1-888-327-4236.

The attached customer reply card identifies your vehicle. Presentation of this card to your dealer will assist in making the necessary correction in the shortest possible time. If you no longer own this vehicle, please let us know by completing the attached and mailing it in the postage paid envelope.

If your vehicle is within the New Vehicle Limited Warranty your dealer may provide you with shuttle service or some other form of courtesy transportation while your vehicle is at the dealership for this repair. Please refer to your Owner's Manual and your dealer for details on Courtesy Transportation.

We are sorry to cause you this inconvenience; however, we have taken this action in the interest of your safety and continued satisfaction with our products.

General Motors Corporation

Enclosure