Required Operations

See the flow chart which shows the general descriptions of the
REQUIRED OPERATIONS. These "REQUIRED OPERATIONS" are as follows:

1. Check for the installation of the previous emission recall completed label (EMR-90-003). If the label is found on the hood, proceed to step 2 below. If the EMR-90-003 Emission Recall Completed Label is NOT found, do EMR-90-003 except the carburetor feedback system testing. While performing EMR-90-003, install the front catalytic converter which is contained in EMR-92-007 emission kit and also replace the Jet Mixture Solenoid valve with the new green valve. Check CO level at 2,500 RPM. If the CO reading is greater than 1.2% at 2,500 RPM, visually check the new Jet Mixture Solenoid Valve installation for misalignment. If the Jet Mixture Solenoid Valve is correctly installed, replace it with another new green Jet Mixture Solenoid Valve. If the CO is still greater than 1.2%, refer to the 1986 Truck Service Manual for troubleshooting procedures which begin in section 14. The EMR-90-003 Emission Recall Bulletin can be found in the 1990 Technical Service Bulletin Manual beginning on Page 381. After completing EMR-90-003, proceed to step 13.

2. Inspect the exhaust manifold heat protector. Check the exhaust manifold and the heat protector for evidence of exhaust leakage. Replace the exhaust manifold if leakage is evident.

3. Replace the front catalytic converter.

4. Check the installation of the choke shim on the carburetor. If the choke shim is missing, obtain the EMR-90-003 emissions kit, then remove the carburetor and install the choke shim contained in the EMR-90-003 emissions kit.

5. Inspect the carburetor's Sub-EGR valve for smooth operation. Remove the carburetor (if not already removed) if cleaning is necessary.

6. Replace the Jet Mixture Solenoid Valve.

7. Check for the installation of modified vacuum hoses. If the vacuum hoses assembly is missing, install the vacuum hoses contained in the EMR-90-003 emission kit.

8. Check the idle speed and ignition timing. Adjust if necessary.

9. Check the Oxygen Sensor output voltage. Replace the Oxygen Sensor if the maximum output voltage is less than 0.6 Volts.

10. Check the CO (Carbon Monoxide) level.

11. Inspect the intermediate harness for correct installation and install it if necessary.

12. Check the existing Service Label. The part number on the label should be MD164141. If not, install the Service Label contained in the EMR-90-003 emission kit.

13. Affix the "EMR-92-007 Emission Recall Completed" Label.

14. Complete and sign the EMR-92-007 emission checklist. Attach the checklist to the repair order.

15. Complete a Vehicle Emission Recall - Proof of Correction form.