Carbureted Engine
- Remove connector and vacuum hose No. 2 from control unit. Connect vacuum pump/gauge to hose. Using an ohmmeter, measure continuity between Black/Yellow and Brown/White wire terminals on connector. There should be continuity.
- Slowly apply vacuum and watch ohmmeter scale. When vacuum increases above 3.9 in. Hg, switch opens and ohmmeter should show no continuity (infinite resistance). Replace vacuum switch A if it does not operate as outlined.