CAMPAIGN: DUAL FUEL TANK RETURN HOSE ROUTING

SUBJECT: DUAL FUEL TANK RETURN HOSE PLUMBING INCORRECT

MODELS: 1985 C6 & C7 MEDIUM DUTY MODEL TRUCKS-CONVENTIONALS WITH DUAL 50 GALLON FUEL TANKS (RPO NE6) AND HEAVY DUTY GAS ENGINE EMISSIONS (RPO HSD)

The National Traffic and Motor Vehicle Safety Act, as amended, provides that each vehicle which is subject to a recall campaign of this type must be adequately repaired within a reasonable time after the owner has tendered it for repair. A failure to adequately repair within 60 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 owner 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 solutions, every effort must be made to promptly schedule appointments with owners and to repair their vehicles as soon as possible. As you will see in reading the attached copy of the letter which is being sent to owners, the owner is being instructed to contact the nearest GMC Zone Office if the dealer does not remedy the condition within five days of the mutually agreed upon service date. If the condition is not remedied within a reasonable time, they are instructed how to contact the National Highway Traffic Safety Administration.

DEFECT INVOLVED

General Motors has determined that some 1985 Medium Duty Conventional Models equipped with dual 50 gallon fuel tanks (RPO NE6) and heavy duty gas emissions (RPO H5D) may have the fuel return hose improperly connected between the switching valve and the fuel tank sending units. This incorrect plumbing causes fuel supplied by one tank to be returned to the other tank. If receiving tank is full, this can result in overfilling and fuel leakage from either the fuel tank vent or upper fuel vapor canister.

This overflow of fuel could ignite on the engine components and cause a fire without prior warning.

Until this condition is corrected, GMC advises use of only one fuel tank.

To correct this condition it is necessary to reposition one of the fuel retum hoses and replace the other return hose with a longer one. Since the possibility exists where fuel may have been pumped into the 2500 cc fuel vapor canister, it will be necessary to replace it.

VEHICLES INVOLVED

Involved are the following 1985 GMC Medium Duty Conventionals with RPO NE6 & H5D, built within the following VIN breakpoints:

Plant From Through ------- -------- -------- Pontiac FV602930 FV617386

The specific vehicles involved in this campaign have been identified by Vehicle Identification Number Computer Listings. These listings are furnished to all involved dealers with the campaign bulletin.

DEALER CAMPAIGN RESPONSIBILITY

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

Whenever a vehicle subject to this campaign is taken into your view or used vehicle inventory, or it is in your dealership for service in the future, you should take the steps necessary to be sure the campaign correction has been made before reselling or releasing the vehicle.

Owners of vehicles recently sold from your new vehicle inventory are to be contacted by the dealer, and arrangements made to make the required modification according to instructions contained in this bulletin.

If no owner's name and address were available to GMC Truck at the time of campaign initiation, the dealer will determine the owner's name and address from the dealership sales records. Please provide this information directly on the second copy of the listing next to the applicable VIN, so that our records may be updated and the appropriate notification mailed to the owner. This second copy should then be submitted to the address listed below in the previously supplied yellow campaign envelopes.

GMC Truck General Motors Corporation 101 Union Street Plymouth, Michigan 48170

OWNER NOTIFICATION

Owners will be notified of this campaign on their vehicles by GMC Truck (see copy of Owner Letter included with this bulletin). A listing of owner names and addresses has been furnished to the involved dealers to enable dealers to follow up with owners involved in this campaign. This listing may contain owner names and addresses obtained from state motor vehicle registration records. The use of such motor vehicle registration data for any other purpose is a violation of law in several states. Accordingly, you are urged to limit the use of this listing to this campaign.

SERVICE PROCEDURE

CAUTION:

To prevent possible accidents when working on fuel systems, provide the appropriate fire fighting and safety equipment in accordance with local fire and safety regulations.

NOTE: The return hoses are the only hoses which may be improperly installed.

1. With ignition key in "OFF" position, disconnect the negative battery cable.

2. Inspect the two fuel retum hoses located at and/or near the fuel sending unit on the right hand fuel tank for correct routing. These hoses are labeled "RTN" and "RETURN" in Figure No. 1.

If vehicle has proper fuel tank return hose routing, no further action is required.

If vehicle has improper fuel tank retum hose routing, complete the remaining steps of this procedure to correct the condition.

3. Locate the hose labeled "RETURN" in Figure No. 1. This illustration shows the correct positioning of the new 15 inch length of fuel retum hose. Cut the nylon tie wrap around the harness block.

4. Remove the old fuel retum hose from the harness block.

5. Insert the new return hose in the block harness.

6. Connect hoses to proper location using existing hose clamps.

7. Do not allow hose to chafe or kink after installation.

8. Using a nylon tie wrap, resecure the harness block.

9. On models equipped with a tilt hood, the 2500 cc evaporative emission canister is located on the right front fender well (see Figure No. 2). On models w/o tilt hood the 2500 cc evaporative emission canister is located in front of the left side fender well. In both cases the 2500 cc emission canister will be the larger of the two canisters on the vehicle.

10. Disconnect all hoses going to it and note the hose locations.

11. Remove old canister and replace with new one.

12. Secure hold down screw and reconnect all hoses to proper location.

13. Reconnect negative battery terminal.

PARTS INFORMATION

Parts are to be obtained from the Warehousing and Distribution Division of General Motors (WDDGM). To ensure that these parts will be obtained as soon as possible, they should be ordered from WDDGM on a C.I.O. order with no special instruction code, but order on an advise code (2).

All vehicles involved in this campaign will require the following parts.

Part *Parts Number Description Allowance Quantity -------- ----------- --------- -------- 17085896 Canister 1

8877974 Nylon Tie Wrap 1

8885522 15 Inches of 1/4" 2.70 1 Fuel Hose Spec #6198-M

*The $2.70 identified in "Parts Allowance" column represents the cost of 15 inches of fuel hose GM Spec #6198-M and 300/o of Dealer Net. This amount is to be placed in the Net Item Amount column of the claim and use type code M.

WARRANTY INFORMATION

Dealers should submit an accurately filled out Warranty Repair Order on each vehicle under this campaign.

Labor Operation *Time Trouble Number Description Allowance Code -------- ------------------- ---------- --------- V2870 Inspect fuel return 0.2 Hrs. 96 hoses for correct routing only.

V2871 Inspect and correct 0.7 Hrs. 96 fuel retum hose routing. Replace emission canister.

*For dealers to receive administration time allowance associated with this campaign, add 0.1 hour to the Labor Operation Time Allowance.

CAMPAIGN IDENTIFICATION LABEL

Each vehicle modified in accordance with the instructions outlined in this product campaign bulletin will require a "Campaign Identification Label". Each label provides a space to include the five (5) digit Dealer Code of the dealer performing the campaign service. This information may be inserted with a typewriter or ballpoint pen.

Each "Campaign Identification Label" is to be located on the radiator core support in an area which will be visible when the vehicle is brought in for periodic servicing by the owner.

Apply "Campaign Identification Label" only on a clean dry surface.

ADMINISTRATIVE PROCEDURE

Procedures covering this campaign are outlined in Section V of your dealership's "GMC Truck Claims Processing Manual" issued April, 1983.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.