System Testing

Fig. 85 HAC Valve Air Filter:

Fig. 86 Testing HAC Valve:

FEDERAL AND CANADIAN MODELS ONLY

1. Remove the cap from the bottom of the HAC valve and inspect the air filter. Fig. 85
2. Clean the filter and reinstall.
3. With the HAC valve at high altitude, (Above 3,930 ft.), and the engine idling, blow into either of the two top air ports on the HAC valve.
4. Check that the valve exhausts air through the air filter. Fig. 86
5. If you are at a low altitude, (Below 2,570 ft.), when performing this test, the valve filter should be closed to air passage.

Fig. 88 Testing Air Flow To Carburetor:

6. Stop the engine and disconnect the two hoses on top of the HAC valve. Fig. 88
7. Blow air into each hose and check that air flows to the carburetor.
8. If any problems are found with the system test, test each component separately.
9. If the BVSV and the check valves test normal, replace the HAC valve.
10. Reconnect all vacuum hoses.