ENGINE SURGE AFTER HOT SOAK CARB. PRIMARY METERING JETS. GMC Truck GMC G Van 1986

MODELS: 1983-86 CABALLEROS EQUIPPED WITH THE 5.0L ENGINE AND THE E4ME QUADRAJET 4BBL CARBURETOR, FEDERAL AND CALIFORNIA EMISSIONS

Some 1983-86 Caballeros may experience an engine surge after a hot soak. A hot soak is when a vehicle has reached operating temperature, then is parked for a short time and restarted. The surge is caused by excessive fuel vapor in the carburetor bowl. This fuel vapor is created by the temperature difference of the carburetor bowl and the fresh fuel delivered from the fuel tank on a restart. If this condition is encountered, it can be reduced by installing new design primary metering jets in the carburetor.

PARTS REQUIRED:

17082634 - Jet Assemblies One package required. 17067279 - Air Horn Gasket One package required.

PART NUMBERS OF CARBURETORS AND MODELS AFFECTED:

Carburetor Model Application ---------- ----- ----------- 17083204 1983 305 (VIN Code H) A/T Federal and California

17083201 1984 305 (VIN Code H) A/T Federal and California

17085202 1985 305 (VIN Code H) A/T Federal and California 305 (VIN Code G) A/T (200-4R) Federal and California

17086003 1986 305 (VIN Code H) A/T Federal and California 305 (VIN Code G) A/T (200-4R) Federal and California

PRIMARY METERING JET REPLACEMENT:

Refer to the Light Duty Service Manual (Section 6C1) for carburetor disassembly and adjustment information.

NOTICE: REPLACING THE PRIMARY METERING JETS IN THE E4ME CARBURETOR REQUIRES REMOVING THE MIXTURE CONTROL SOLENOID AND THE FLOAT. THEREFORE, THE ADJUSTMENTS AFFECTING THESE COMPONENTS MUST BE CHECKED AND ADJUSTED, IF NECESSARY, DURING REASSEMBLY. THE FOLLOWING STEPS SHOULD BE FOLLOWED AS A GENERAL GUIDE TO THE REPLACEMENT OF THE METERING JETS.

Disassembly

1. Remove air cleaner.

2. Remove air bleed valve cover.

3. Remove air horn.

4. Remove solenoid adjusting (lean stop) screw and solenoid (rich) stop screw plugs.

5. Remove mixture control solenoid assembly.

NOTICE:IF TOOL #J-33815-1 OR EQUIVALENT IS NOT USED FOR REINSTALLING MIXTURE CONTROL SOLENOID IT WILL BE NECESSARY TO RECORD THE NUMBER OF TURNS WHEN REMOVING ADJUSTING (LEAN STOP) SCREW.

6. Remove float.

7. Remove primary metering jet assemblies.

Reassembly

1. Install new primary metering jet assemblies.

2. Install float and adjust if necessary. The specification for float level is 11/32".

3. Install mixture control solenoid using tool, #J-33815-1 or equivalent or by setting adjusting (lean stop) screw to the same number of turns recorded in step #5 of Disassembly.

4. Install air horn with new gasket.

5. If carburetor has a removable pump lever hinge pin, install the cotter pin supplied in air horn gasket package, following package instructions.

6. Check mixture control solenoid plunger travel: should be 4/32". If not, adjust solenoid (rich) stop screw to obtain correct travel.

7. Install solenoid adjusting (lean stop) and solenoid (rich) stop screw plugs.

8. Check mixture control solenoid dwell with engine running in closed loop and canister purge disconnected. Dwell should read approximately 30 degrees at idle. If not, adjust air bleed valve to obtain.

9. Reconnect canister purge and install air cleaner housing.

Labor Time to perform this procedure is 1.2 hours.

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.