EXPERTEC TSB (94C57A)

EXPERTEC TSB

TECHNICAL SERVICE BULLETIN

CAMPAIGN: POOR THROTTLE - RESPONSE, STALLING, MISFIRE

Model(s): 1994 GMC C/K Trucks and G Vans with 6.5L Diesel Engine (RPO'S L65, L56 and L49 with Automatic and/or Manual Transmission)

Bulletin No.: GMC 94C57A

Date: 10/24/1994

BULLETIN ILLUSTRATION LIST

SERVICE INFORMATION

THIS BULLETIN CANCELS AND REPLACES 94-C-57 ISSUED OCTOBER 1994. DESTROY ALL COPIES OF 94-C-57. REVISIONS HAVE BEEN MADE TO THE SERVICE PROCEDURES, WARRANTY INFORMATION, AND THE TIMING PROCEDURE. ALL REVISIONS ARE DISTINGUISHED BY SHADED BOXES.

General Motors has determined that CERTAIN 1994 GMC C/K trucks and G vans may experience poor throttle response, stalling, misfire, poor cold or hot starting, extended cranking of the starter with a hot engine, and/or your vehicle will start and then stall when the engine is hot. Vehicles with manual transmissions may also experience deceleration stall and poor acceleration performance.

* Poor cold starting includes an extended crank time (more than 4 seconds at temperatures of 0 degrees Fahrenheit and above), rough idle, white smoke and/or start then stall. A cold start is defined as starting the engine after shut down for more than three hours.

* No start or extended cranking of the starter with a hot engine, starting then stalling when the engine is hot, is defined as starting the engine within three hours of shutdown (extended cranking time with a hot engine is defined as more than 4 seconds cranking time).

To correct these condition, involved vehicles will be updated with a service parts kit and a PCM PROM.

VEHICLES INVOLVED

Involved are CERTAIN 1994 GMC C/K trucks and G vans built within the following VIN breakpoints:

Model	Year	Plant	From	Through
Suburban w/L65	1994	Janesville	SOP	1GKGC26F1RJ766442
Yukon w/L56	1994	Janesville	SOP	1GKEK18S2RJ764990
Pickup w/L65	1994	Janesville	SOP	1GDKC34F4RJ524402
Pickup w/L65	1994	Pontiac East	SOP	1GTGC29F1RE560831
Pickup w/L56	1994	Pontiac East	SOP	1GTFC24S5RE560802
Pickup w/L49	1994	Pontiac East	SOP	1GTFC24P7RE560778
Pickup w/L56	1994	Oshawa	SOP	2GTEK19S0R1585416
Pickup w/L49	1994	Oshawa	SOP	2GTEK19P6RI585335
Van w/L49	1994	Flint	SOP	EOP

The specific vehicles involved in this campaign have been identified by Vehicle Identification Number (VIN) Computer Listings. These listings are furnished to all involved dealers with the campaign bulletin. Dealers should confirm vehicle eligibility through VISS (Vehicle Information Service System) or SERVICENET prior to beginning campaign repairs.

DEALER CAMPAIGN RESPONSIBILITY

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

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.

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

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

If the name and address of the owner of an involved vehicle was unavailable to GMC Truck Division at the time of campaign initiation, the dealer must 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.

General Motors Corporation

101 Union Street

Plymouth. Michigan 48170

OWNER NOTIFICATION

Owners will be notified of this campaign on their vehicles by GMC Truck Division (see copy of owner letter included with this bulletin). In addition, the owners will also be provided a pamphlet entitled "How To Get The Most From Your EFI Diesel Truck". 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

The following checks must be performed to qualify the engine support systems.

A diagnostic check sheet (Attachment 1) has been provided to assist in this process, and must be attached to the repair order. (This diagnostic check sheet should be reproduced locally.)

1. Check PROM ID using Tech 1. See Parts Information Section of this bulletin for ordering replacement PROM. If the new PROM is currently in the truck, do not replace.
2. Check for diagnostic trouble codes (DTCs), both history and current. Use the 1994 Diesel Service Manual Supplement for diagnosis and correction. Clear all current and history DTCs before proceeding.
3. Check wiring connections at batteries, relay center, engine grounds and wiring grounds for secure and complete attachment (Attachment 2).
4. Check air filter, clean or replace as necessary.
5. Check cold cranking RPM, spec: 100 RPM cold engine (Attachment 3).
6. Check fuel supply system pressure, spec: 3 psi minimum at idle (Attachment 4).
7. Check glow plugs (Attachment 5).
   NOTE: Once above procedures have been completed, install service kit which contains a visor label (engine starting procedure), electronic filter harness, and two stage housing pressure regulator (See Attachment 6 and 7 for installation procedure). Install replacement PROM, using the Parts Information Section below.
8. Check for air in fuel system (See Attachment 8) for procedure.
9. Relearn the TDC Offset. If the relearned value is between +0.75 and -1.75, continue to the next step. If the value is not between +0.75 and -1.75, reset pump timing following the procedure shown in Attachment 9.
10. Check the fuel rate at idle using Tech 1 (maximum spec. 13mm manual transmission or 15 mm for automatic transmission). If out of specification, check fuel quality with a hydrometer (J34352). Refer to appropriate service manual for procedure and empty fuel system and refill with known good fuel source if required.
    NOTE: IF OWNERS CONCERN WAS HOT START OR EXTENDED CRANK HOT OF MORE THAN 4 SECONDS BEFORE STARTING, CONTINUE WITH THE FOLLOWING DIAGNOSIS.
11. Block the radiator and bumper holes, operate the engine with A/C off at 3400 RPM in neutral until coolant temperature reaches 220 degrees Fahrenheit as indicated on the Tech 1, or
12. Shut off engine and let the vehicle hot soak for 20-25 minutes.
13. Using a timer that accurately reads "seconds" record crank time.
14. If crank time exceeds 4 seconds check cranking speed, spec: 170-180 RPM (Attachment 3).
15. If crank speed is within specification and crank time exceeds 4 seconds replace the injection pump.
    NOTE: Injection pumps are to be exchanged through Stanadyne. DO NOT order from GMSPO.
16. Change engine oil, filter and lubricate chassis.
17. Install Campaign Identification Label.

PARTS INFORMATION

Parts are to be obtained from General Motors Service Parts operation (GMSPO).

To ensure parts are obtained as soon as possible, order them from GMSPO on a C.I.O. order with no special instruction code but order under an advise code (2). Parts are available.

Injection pumps are currently available through a Stanadyne Dealer (see GM Corporate Service Bulletin 376302, dated September 1993, for Stanadyne Dealer near you.)

Part Number	Description	Quantity
12553873	Service Kit	1
See Chart*	PROM	1

To order correct PROM for vehicle, check current Scan I.D. with Tech 1, then cross reference the Scan I.D. using the chart listings below.

All PROMs listed below provide 1068 RPM fast idle upon request when properly modified.

Body Style/Series	Current Scan ID	New PROM P/N	New B/C (PROM Labels)	New PROM ID (Scan Tool)
Pickup C1-2	6925	16211620	BMXZ	1605
Pickup K1-K2, Yukon K1	6935	16211623	BMYA	1615
Pickup C1-2	3285,7415	16210063	BMRK	9935
Pickup K1-2, Yukon K1	3295,7425	16210068	BMRL	9945

Body Style/Series	Current Scan ID	New PROM P/N	New B/C (PROM Labels)	New PROM ID (Scan Tool)
Pickup C/K2-3, Chassis Cab C/K3, Suburban C/K2	6945,3345,7375	16210150	BMSD	0145
HD Chassis Cab C3/C5B	6895,3305,7385	16210156	BMSF	0155
Pickup C/K2-3, Chassis Cab C/K3	3735.7325	16210072	BMRM	9955
Suburban C/K2	3325,7345	16210082	BMPP	9975
HD Chassis Cab C3/C5B	3355,7335	16210078	BMFN	9965
Motorhome P3	1025	16211628	BMYB	1625
Ambulance C/K 2-3	3685	16210093	BMRT	0005
HD Ambulance C3/C5B	3695	16210097	BMRU	0015
Pickup C/K2-3, Chassis Cab C/K3	6465	16210217	BMSW when properly modified.	0275
Suburban C/K2	6475	16210226 - These PROMs provide 1360 RPM fast idle upon request,	BMSY	0295
HD Chassis Cab C3/C5B	5755	16210220	BMSX	0285
- C5B: 15,000 LB GVW

Body Style/Series	Current Scan ID	New PROM P/N	(PROM Labels)	New B/C New PROM ID (Scan Tool)
Pickup C/K2-3	6905,2225,3335, 7395,0165	16215261	BNTF	175
HD Chassis Cab C3/C5B	6915,2235,3315, 7405,0175	16215263	BNTH	5185
HD Chassis Cab C3/C5B	8605,0185	16215266	BNTJ	5195
Pickup C/K2-3	3365,7355,9985	16215253	BNTB when properly modified.	5145
Chassis Cab C3/C5B	3375,7365,9995	16215256 - These PROMs provide 1360 RPM fast idle upon request,	BNTC	5155
HD Chassis Cab C3/C5B	8595,0025	16215258	BNTD	5165
- C5B: 15,000 LB GVW

Body Style/Series	Current Scan ID	New PROM P/N	New B/C (PROM Labels)	New PROM ID (Scan Tool)
Van G2	6835,3215,7435	16210182	BMSL	0195
Van G2	6845,3225,7445	16210187	BMSM	0205
Pickup C1	6855,3235,7455	16210190	BMSN	0215
Pickup C1	6865,3245,7465	16210196	BMSP	0225
Pickup C2, K1-2	68 75,3255,7475	16210199	BMSR	0235
Pickup C2, K1-2	6885,3265,7485	16210203	BMSS	0245

Body Style/Series	Current Scan ID	New PROM P/N	New B/C (PROM Labels)	New PROM ID (Scan Tool)
Pickup C1	6815,3275, 7495,0255	16215268	BNTN	5235
Pickup C2, K1-2	6825,3205, 7505,0265	16215271	BNTP	5245

WARRANTY INFORMATION

Dealers should submit a warranty claim on each vehicle completed under this campaign.

CAMPAIGN IDENTIFICATION LABEL

Each vehicle corrected 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 campaign number and five (5) digit dealer code of the dealer performing the campaign service. This information may be inserted with a typewriter or ball point 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 Warranty Claims Processing Manual" #P9119 Rev. 2/94.

CUSTOMER NOTIFICATION OF RECALL

Dear GMC Truck Owner:

Your complete satisfaction with your 1994 GMC Truck, equipped with a 6.5L Electronic Fuel Injection (EFI) Diesel Engine, is most important to GMC Truck. We want your 6.5L diesel to satisfy all your driving needs and wish to inform you that enhancements are available to improve your engine's driveability.

The 1994 6.5L EFI Diesel Engine in your truck is equipped with an electronic fuel injection pump which is controlled by a powertrain control module (or computer). CERTAIN Trucks may exhibit some driveability concerns such as poor throttle response, stalling, misfire, poor hot or cold starting, extended cranking of a hot engine, or stalling after start. Trucks equipped with manual transmissions may exhibit poor acceleration from start characteristics or may stall during deceleration. To address these concerns, your GMC truck dealer can install some recently developed enhancements which will improve the overall driving pleasure of your vehicle. These enhancements will be installed at no charge to you.

Instructions for performing this service have been sent to your GMC Truck dealer. Please contact your dealer to arrange a convenient service appointment. Please be prepared to describe the specific concern or symptom your vehicle exhibits. This will assist the dealer in accurately assessing the situation. Since some of the required parts are unique to your specific vehicle, a short first visit to the dealer may be necessary to determine the appropriate parts needed for your vehicle. On the second visit, the new parts will be installed an may require between 1 to 6 hours to install, depending on the repairs required.

We've also enclosed a brochure which describes some of the features of the 6.5L Diesel Engine and how it differs from diesel engines that utilize mechanical injection systems. Please take the time to read this important information.

The enclosed postage paid owner reply card identifies your vehicle.

Presentation of this card to your. dealer will assist in making the necessary correction to your vehicle in the shortest possible time. If you have sold or traded your vehicle, please furnish us the complete name and address of the person you sold or traded your vehicle to and return the card to us.

We sincerely regret the inconvenience or concern this situation may cause you. Your satisfaction with GMC products is of utmost concern to us. We have taken this action to ensure your GMC Truck provides years of pleasurable driving experience.

GMC TRUCK DIVISION GENERAL MOTORS CORPORATION