LACK OF POWER HESITATION ON ACCEL. (INSPECT AIR CLEANER)

********************************************************************** CONDITION: SOME OWNERS OF 1992-93 MODEL YEAR M/L VANS EQUIPPED WITH 4.3L (L35) V6 (VIN W) ENGINES MAY REPORT A LACK OF POWER OR HESITATION WHEN ACCELERATING UNDER HOT DRIVING CONDITIONS. THE ENGINE WILL RUN FINE OTHERWISE AND FUEL ECONOMY WILL BE NORMAL. THE ENGINE WILL NOT MISS, SURGE, OR HAVE A ROUGH IDLE. IN GENERAL, NO DIAGNOSTIC TROUBLE CODES (DTC) WILL BE SET.

CAUSE:

THE OUTLET DUCT (DUCT BETWEEN THE AIR CLEANER AND THE THROTTLE BODY) MAY NOT HAVE ENOUGH RIGIDITY TO WITHSTAND A RAPID PRESSURE DROP UNDER HOT DRIVING CONDITIONS AND MAY TEMPORARILY DISTORT.

CORRECTION:

FOLLOW THE DIAGNOSTIC PROCEDURES FOR LACK OF POWER IN THE APPRO- PRIATE LIGHT DUTY TRUCK FUEL AND EMISSIONS SERVICE MANUAL. IF NO CONDITION IS FOUND CAUSING THIS SYMPTOM, INSPECT THE OUTLET AIR DUCT. DETERMINE IF THE LATEST DESIGN OUTLET AIR DUCT HAS BEEN INSTALLED (SEE ATTACHED DIAGRAM OF THE ORIGINAL AND LATEST OUTLET AIR DUCT). IF THE VEHICLE DOES NOT HAVE THE LATEST OUTLET AIR DUCT INSTALLED AND WAS BUILT BEFORE THE FOLLOWING BREAKPOINTS,:

CHEVROLET PB181471 GMC PB532742

USE THE FOLLOWING PROCEDURE: 1. REMOVE ORIGINAL OUTLET DUCT. 2. INSPECT AIR CLEANER AND REMAINING DUCTS FOR OBSTRUCTIONS. REMOVE ANY OBSTRUCTIONS FOUND. 3. INSTALL OUTLET DUCT P/N 25099916 (SEE FIGURE).

SERVICE PARTS INFORMATION: PART NUMBER DESCRIPTION QUANTITY ----------- ----------- -------- 25099916 DUCT-OUTLET 1

PARTS ARE CURRENTLY AVAILABLE FROM GMSPO.

WARRANTY INFORMATION LABOR OPERATION DESCRIPTION TIME ALLOWANCE --------------- ----------- -------------- J5000 R + R OUTLET DUCT SEE APPROPRIATE LABOR TIME GUIDE

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.

COPYRIGHT 1993, GM POWERTRAIN DIVISION, GENERAL MOTORS CORPORATION. ALL RIGHTS RESERVED.