EXTENDED ENGINE CRANKING TIME DURING HOT ENGINE RESTART IN. Chevrolet Chevy Suburban

SUBJECT: EXTENDED ENGINE CRANKING TIME DURING HOT ENGINE RESTART IN HIGH AMBIENT TEMPERATURE CONDITIONS (ALLOW ENGINE TO IDLE PRIOR TO SHUTDOWN)

MODELS: 1996-99 CHEVROLET, GMC C/K, G, P MODELS WITH 6.5L DIESEL ENGINE (VINS F, S, Y - RPOS L65, L56, L57)

CONDITION:

SOME OWNERS OF DIESEL EQUIPPED VEHICLES MAY COMMENT ON AN EXTENDED ENGINE CRANKING TIME DURING A HOT RESTART IN HIGH AMBIENT TEMPERATURES OF 38 C (100 F), ESPECIALLY WHEN PULLING A LOAD. THIS CONDITION NORMALLY WILL OCCUR AFTER THE VEHICLE HAS BEEN SHUT OFF AT FULL OPERATING TEMPERATURE AND THEN RESTARTED AFTER APPROXIMATELY 15-90 MINUTES. IT IS SOMETIMES CALLED A "HOT SOAK". NO OTHER DRIVEABILITY SYMPTOMS HAVE BEEN NOTED AND THE MIL IS NOT ILLUMINATED.

CAUSE:

VISCOSITY OF THE DIESEL FUEL FOLLOWING A HOT SOAK BECOMES TOO LOW TO BE PROPERLY PRESSURIZED BY THE FUEL INJECTION PUMP ON RESTART DURING THESE PERIODS OF HIGH UNDERHOOD TEMPERATURES. THIS LOWER PRESSURE IS INSUFFICIENT TO POP THE FUEL INJECTION NOZZLES AND PROPERLY DELIVER FUEL TO THE ENGINE.

CORRECTION:

IF THE AMBIENT TEMPERATURE IS 38 C (100 F) OR GREATER, ESPECIALLY WHEN PULLING A LOAD, CUSTOMERS SHOULD ALLOW THE VHEICLE TO IDLE FOR 5-10 MINUTES PRIOR TO SHUTTING OFF THE ENGINE. THIS WILL ALLOW THE ENGINE TEMPERATURE TO STABILIZE AND MINIMIZE HOT RESTARTING TIME.

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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.