BACKFIRE/HESITATION/ LOW POWER (INSTALL PROM). GMC Truck GMC K Pickup

********************************************************************** SUBJECT: BACKFIRE/HESITATION (SAG) ON LAUNCH, LOW POWER (SURGE) IN HIGH GEAR

MODELS: 1993 CHEVROLET AND GMC C/K TRUCKS WITH 4.3L ENGINE (VIN Z - RPO LB4) AND MANUAL TRANSMISSION **********************************************************************

CONDITION:

SOME OWNERS MAY COMMENT ON ONE OR MORE OF THE FOLLOWING CONDITIONS.

1. BACKFIRE ON INITIAL ACCELERATION FROM A STANDING START AND/OR BACKFIRE WHEN ACCELERATING AT LOW SPEEDS IN HIGH GEAR.

2. HESITATION OR SAG ON INITIAL ACCELERATION FROM A STANDING START.

3. LOW POWER OR PERCEIVED ENGINE SURGE WHEN ACCELERATING AT PART THROTTLE IN HIGH GEAR AND/OR LOW POWER AT PART THROTTLE WHEN CLIMBING HILLS IN HIGH GEAR.

CAUSE:

SYSTEM/COMPONENT VARIABILITY.

CORRECTION:

INSTALL THE CORRECT SERVICE PROM FROM THE TABLE BELOW.

PROM INFORMATION: ALL PROMS ARE NA1 (LESS THAN 8500 GVW) OLD TRANS EMIS. SERVICE B/C SCAN B/C VEHICLE RPO AXLE RPO CLASS PROM KIT CODE ID CODE ------- ----- -------- ----- -------- ---- ---- ---- C1 MG5 GU4,GU6 NA5/NA6 16202468 BKRF 2465 BCMR (ABOVE CALIBRATION IS FOR C1500 TRUCKS WITH A SHIFT LIGHT.)

C1,C2,K1,K2 MG5/MT8 GU4,GU6,GT4 NA5/NA6 16202472 BKRH 2475 BCMS

C1,K1 MG5/MT8 GU4,GU6,GT4 NB2 16202464 BKRD 2455 AZHW

PARTS ARE CURRENTLY AVAILABLE FROM GPSPO.

LABOR TIME:

LABOR OPERATION: T0500 - PROM, PCM-REPLACE LABOR TIME: 0.6 HOUR

FIGURES: 0

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.