Engine - Hot Hesitation/Cold Detonation
87chevy20 REISSUENumber: 87-181
Section: 6E
Date: Oct., 1987
Subject: DRIVEABILITY: HOT HESITATION/COLD DETONATION
Model and Year: 1987 CAPRICE, CAMARO, MONTE CARLO, EL CAMINO WITH 5.0L LG4 ENGINE (ENGINE CODE H)
TO: ALL CHEVROLET DEALERS
This bulletin is being reissued to correct an error in two PROM part numbers listed on page 2. The part numbers affected are indicated by an asterisk (*) and are correct as printed in this revision.
All copies of 87-181 (Section 6E) dated July 1987 should be destroyed and replaced with 87-181 reissue.
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:
^ Detonation prior to the engine fully warming up.
^ 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.
Applicable VIN Numbers
Service PROM Usage Table
Service Procedure:
1. Disconnect negative battery cable.
2. Install appropriate service PROM.
3. Remove air cleaner.
4. Remove air horn. (Refer to Section 6C1 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.
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