HARD STARTING COLD-6.2L DIESEL (INSTALL NEW REGULATOR/PUMP)

SUBJECT: HARD STARTING COLD (INSTALL NEW REGULATOR VALVE ASSEMBLY AND PUMP)

VEHICLES AFFECTED: 1982-89 ALL TRUCKS W/6.2L DIESEL

Condition:

----------- Some 1982-89 trucks with 6.2L diesel engine may experience a cold hard starting condition. This condition may occur even though the glow plug system is operating properly.

Cause:

------- Air leaks in either the return or suction side of the fuel system. These air leaks cause loss of fuel prime in the injector pump after engine shutdown.

Correction:

------------ On the return side, a new HPCA (Housing Pressure Cold Advance) regulator valve assembly, P/N 10149645 must be installed. This valve and seal replaces the existing ball check regulator valve in the injector pump. On the suction side, install new fuel pump, P/N #25116503 which now uses a new ventless check valve to prevent fuel drain back. Both the return and suction side must be corrected at the same time. This correction is for all 1982-89 trucks except 1988/89 C/K trucks which uses an electric pump with integral check valve. We still require replacement of the HPCA valve on the Stanadyne injector pump.

Parts are expected to be available on October 21, 1991.

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.