HOT HESITATION AT NORMAL OPERATING TEMPERATURES

MODEL AND YEAR: 1987 CAPRICE, CAMARO, MONTE CARLO, EL CAMINO WITH 5.0L LG4 ENGINE (ENGINE CODE H)

This bulletin cancels and supersedes Chevrolet Dealer Service Bulletin 87-31 (Sec. 6C) dated Dec., 1986. All copies of 87-31 should be destroyed. Bulletin 87-31 reissue provides additional repair information for the described condition.

Some early passenger cars equipped with 5.0L (LG4) engines and having VIN numbers prior to those listed below may experience one or both of the following driveability conditions:

o Detonation prior to the engine fully warming up.

o Hesitation during a sharp tip-in maneuver with a fully warmed up engine, (sometimes called "pump slug").

These conditions may be improved by installation of an accelerator pump check ball spring, P/N 17069583), and the appropriate service"PROM from the table below:

Applicable VIN Numbers

Model Plant Prior to VIN Number ----- ----- -------------------

Monte Carlo Arlington (R) 119290

El camino Pontiac (P) 136041

Ramos (S) 909546

Caprice Fairfax (X) 208979 (Federal Emissions) 209228 (California Emissions)

Clark St. (9) 145315

Camaro Van Nuys (L) 133181 (Chevrolet) 223698 (Pontiac)

Norwood (N) 149294 (Chevrolet) 232459 (Pontiac)

Service PROM Usage Table

Caprice (LG4)

2 and 4 Door All Axles Fed. Emis. 16077203 Station Wagon 2.73 Axle Fed. Emis. 16077198 Station Wagon 3.08 Axle Fed. Emis. 16077194

2 and 4 Door All Axles Calif. Emis. 16077207 Station Wagon 2.73 Axle Calif. Emis. 16077563 Station Wagon 3.08 Axle Calif. Emis. 16077568

Monte Carlo and El Camino (LG4)-

4 Spd. Auto. 2.41, 2.56 Axle Fed. Emis. 16077306 4 Spd. Auto. 3.08 Axle Fed. Emis. 16077317 3 Spd. Auto. 2.41, 2.73 Axle Fed. Emis. 16077321

4 Spd. Auto. 2.41, 2.56 Axle Calif. Emis. 16077333 4 Spd. Auto. 3.08 Axle Calif. Emis. 16077325 3 Spd. Auto. 2.41, 2.73 Axle Calif. Emis. 16077329

Camaro (LG4)

4 Auto. 2.73/2.77 Axle Fed. Emis. P195/P215 Tires 16077174 4 Auto. 2.73 Axle Fed. Emis. P245 Tires 16077573

4 Auto. 2.73/2.77 Axle calif. Emis. P195/P215 Tires 16077185 4 Auto. 2.73 Axle calif. Emis. P245 Tires 16077577

Service Procedure:

1. Disconnect negative battery cable.

2. Install appropriate service PROM.

3. Remove air cleaner.

4. Remove air horn. (Refer to Section 6Cl of Service Manual if details of disassembly are needed.)

5. Remove solenoid adjusting screw plug from air horn.

6. Remove solenoid plunger, air horn gasket, pump assembly, metering rods and float bowl insert.

7. Count and record the number of turns to the solenoid adjusting screw required to lightly bottom the mixture control solenoid.

8. Remove the mixture control solenoid assembly.

9. Remove float and assembly.

10. Remove pump discharge plug.

11. Install accelerator pump check ball spring, P/N 17069583. See Illustration.

12. Reinstall pump discharge plug.

13. Reinstall float and needle. (Hook needle pull clip over float lever crossbar facing seat. DO NOT hook through holes in float lever.)

14. Reinstall mixture control solenoid.

15. Reinstall solenoid adjusting screw and turn it to lightly bottom solenoid, then back out the number of turns counted during disassembly.

16. Reinstall float bowl insert, metering rods, pump assembly, air horn gasket and solenoid plunger.

17. Reinstall air horn.

18. Reinstall solenoid adjusting screw plug.

19. Reinstall air cleaner.

20. Reconnect negative battery cable.

Labor Operation Number: T1217

Labor Time: Caprice .9 Hour Monte Carlo .9 Hour El Camino .9 Hour Camaro 1.1 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.