1978-79 Models
- With engine cold, start engine and check for vacuum at distributor vacuum retard unit. There should be no vacuum present. If vacuum is present, disconnect thermo sensor. If vacuum remains, replace ignition solenoid valve. If vacuum drops slightly, replace thermo sensor. See Fig 1.
- With engine idling at normal operating temperature, there should be vacuum to distributor vacuum retard unit. If no vacuum is present, check for vacuum at ignition solenoid valve. If no vacuum is present at solenoid valve, clean intake manifold vacuum port.
- If there is still no vacuum at solenoid valve, check voltage at solenoid valve. If voltage is present, replace solenoid valve. If no voltage is present, check for continuity across thermo sensor. If continuity exists, check wiring and fuses. Repair as necessary. If no continuity exists, replace thermo sensor.
- Raise engine speed to 3000 RPM. Check for vacuum on carburetor side of delay valve. If no vacuum is present, clean carburetor port or hose as necessary. Pull off other hose and remove delay valve. Connect hand-held vacuum pump to one end of delay valve. Cover other end with finger, apply vacuum, and check for leaks.
- Attach hand-held vacuum pump to distributor side of delay valve. Apply vacuum and make sure there is no restriction. Attach hand-held vacuum pump to carburetor side of delay valve and apply vacuum. Vacuum should decrease from 15 to 5 in. Hg in 5-10 seconds for the Black/Yellow delay valve or in 15-25 seconds for the Black/Green delay valve.
- After reinstalling delay valve, attach vacuum pump to advance side of distributor diaphragm and start engine. Apply vacuum and make sure distributor advances and diaphragm does not leak. Repeat procedure on retard side of diaphragm.
Courtesy of AMERICAN HONDA MOTOR CO., INC.