DRIVEABILITY EXHAUST ODOR INSPECTION/MAINTENANCE/PROM. GMC Truck Safari

MODELS: 1987 "M" VANS EQUIPPED WITH 4.3L ENGINES (VIN CODE Z) FEDERAL EMISSIONS AND AUTOMATIC 4-SPEED TRANSMISSIONS

Some 1987 "M" vans equipped with 4.3L engines (VIN Code Z) may experience one or both of the following conditions:

1. Hydrogen sulfide related odor typically described as "rotten egg smell" at idle.

2. Difficulty in meeting state exhaust emission inspection/maintenance (I/M) testing requirements.

If the condition described cannot be repaired using norm al service procedures, a revised calibration PROM and a connector bleed assembly should be installed. The appropriate part numbers are as follows:

Part Description Part Number ---------------- ----------- PROM 16082087 Connector Bleed Assembly 10105820

Installation Procedure

1. Using a Scan tool, check PROM I.D. The Scan tool I.D. for PROM Part Number 16082087 is 2261. M vans assembled after the following breakpoints have the latest PROM.

Chevrolet 217841

GMC 529224

If the vehicle is not equipped with this PROM, the PROM must be replaced.

2. Disconnect the negative battery cable.

3. Disconnect the EGR vacuum line currently on port J on the front of the TBI unit, see Figure No.1.

4. Install connector bleed assembly, P/N 10105820.

5. Connect EGR vacuum line removed from port J to the open end of the connector bleed assembly.

6. Reconnect the negative battery cable.

Use the following labor operations and times:

Labor Operation Time Description --------- ---- ----------- T7455 .3 Hr. Identify existing PROM install bleed connector.

Add .2 Hr. If necessary to change PROM (not I.D. 2261)

Object Number: 79510 Size: FS

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.