System Test
- With engine at normal operating temperature, remove air cleaner. DO NOT cap any vacuum fittings opened by home removal (leakage needed for test).
- Disconnect hose to idle enrichment valve at plastic connector. Connector has a filtered bleed which will interfere with test, so it must be removed. Start engine and place fast idle screw on slowest step of fast idle cam. Connect 3-4' (1-1.3 m) length of hose to enrichment valve.
- Using a hand pump, apply vacuum to end of hose and listen for engine speed change. If engine speed can be controlled by vacuum, diaphragm and air valve are operating correctly. If speed cannot be controlled by vacuum, replace valve assembly on Holley carburetors. Proceed to next step for Carter carburetors.
- Place finger on the other plug, over air inlet passage. Listen for engine speed change. If speed can be controlled, diaphragm is leaking or air valve is stuck open. If speed cannot be controlled, air valve is stuck closed. Clean air valve or replace diaphragm, as necessary.