See Figure 1
These valves are used in the evaporative emission system to control vapor flow from the carburetor bowl to the carbon canister. With either valve, the flow path from the carburetor bowl to the carbon canister is closed by manifold vacuum, when the engine is running. The thermostatic valve closes the bowl to canister flow path when the temperature of the valve is 90°F or less. When the temperature of the valve is 120°F or more, the valve is open unless closed by manifold vacuum.
The vacuum vent valve should flow air when no vacuum is applied and should not flow air with vacuum applied at the vacuum nipple. This test also applies to the vacuum/thermostatic vent valve when it is at a temperature of 120°F or more. At a temperature of 90°F or less, the valve should not pass vacuum.
REMOVAL & INSTALLATION
- Disconnect the negative battery cable.
- Label and disconnect the hoses from the fuel bowl thermal vent valve.
- Remove the fuel bowl thermal vent valve.
- Installation is the reverse of the removal procedure.