HARD START, NO START, START STALL, ROUGH IDLE. Chevrolet Chevy P RV/Van/Commercial Chassis 1996

SUBJECT: HARD START, NO START, START STALL, ROUGH IDLE, STUMBLE AND LACK OF POWER (NEW OPTICAL SENSOR AND CERAMIC ROLLERS)

MODELS: 1994-96 CHEVROLET AND GMC C/K, G, P TRUCKS WITH 6.5L DIESEL ENGINE (VINS F, S, P--RPOS L65, L56, L49)

CONDITION:

SOME OWNERS MAY COMMENT ON THE FOLLOWING CONCERNS: HARD/NO START, START STALL, ROUGH IDLE, AND ENGINE STUMBLE WHEN OPERATING UNDER HIGH TEMPERATURES AND LOAD CONDITIONS. RELATED DTCS: (1996: P0251, P0370, P1216, P1217), (1994-95: CODES 17, 18, 35, 36).

CAUSE:

A DISTRESSED OPTICAL SENSOR CIRCUIT BOARD MAY CAUSE NO OR IMPROPER CAM SIGNALS WHICH AFFECTS PUMP TIMING. ALSO, LOW LUBRICITY FUEL MAY RESULT IN WORN INJECTION PUMP CAM ROLLERS CAUSING LOW FUEL OUTPUT.

CORRECTION:

AN ENHANCED FUEL INJECTION PUMP WAS RELEASED BEGINNING WITH THE 1997 MODEL YEAR THAT CONTAINS AN IMPROVED OPTICAL SENSOR. IN ADDITION, NEW CERAMIC ROLLERS ARE ALSO RELEASED WHICH WILL HELP PREVENT ROLLER WEAR DUE TO LOW LUBRICITY FUELS.

SERVICE PROCEDURE AS WITH ANY COMMENT, THE CONDITION MUST BE DUPLICATED BEFORE ATTEMPTING TO DO ANY REPAIRS AND A THOROUGH INVESTIGATION DONE TO DETERMINE THE PRIMARY CAUSE OF THE CONCERN. IF DTCS ARE PRESENT, REFER TO SECTION 6E OF VOLUME 2 OF THE SERVICE MANUAL TO TROUBLESHOOT ANY/ ALL DTCS. FOR OTHER DRIVEABILITY SYMPTOMS, USE THE SAME MANUAL.

1994-96 MODEL YEAR SERVICE INJECTION PUMP 1. 1996 MODEL YEAR 0-12 MONTHS, 50,000 MILES. WILL BE SERVICED USING A NEW REPLACEMENT PUMP, PART NUMBER 12558156-MODEL NO. 5288 TO REPLACE A PART NUMBER 10225930 INJECTION PUMP (REFERENCE BULLETIN 57-63-04A FOR 1996 INJECTION PUMP EXCHANGE PROGRAM POLICY).

2. PART NUMBER 10225930, MODEL NO. 5067. INJECTION PUMP WILL BE REBUILT BY THE STANADYNE DEALER AND IDENTIFIED BY STAMPING MODEL S5288 AND PART NUMBER 12558156 ON THE MANUFACTURER'S PLATE. IN ADDITION A "GREEN" TAG WILL BE ATTACHED TO THE FRONT OF THE PUMP.

3. PART NUMBER 10225929, MODEL NO. (5068). INJECTION PUMP WILL BE REBUILT BY THE STANADYNE DEALER USING THE NEW OPTICAL SENSOR AND CERAMIC ROLLERS. THE PUMP WILL NOT BE IDENTIFIED WITH A NEW MODEL NUMBER BUT WILL HAVE THE "GREEN" TAG ON THE FRONT OF THE INJECTION PUMP AND STAMPED (S5068) ON THE NOMENCLATURE LABEL.

4. ANY NEW INJECTION PUMP (PART NUMBER 10225930) WILL BE SUPERSEDED TO THE NEW PART NUMBER 12558156. HOWEVER, IF A NEW PUMP PART NUMBER 10225929 IS ORDERED IT WILL BE AN UPDATED MODEL 5068 WITH THE "GREEN" TAG HUNG FROM THE FRONT OF INJECTION PUMP.

WARRANTY INFORMATION FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR LABOR OPERATION DESCRIPTION TIME

J5955 PUMP, FUEL INJECTION USE PUBLISHED LABOR TIME (DIESEL) REPLACE PLUS 0.2 HRS. FOR ADMINISTRATION TIME.

FIGURES: 0 ATTACHMENTS: 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.