Bowl Vent Valve: Testing and Inspection

Fig. 1 Bowl ventilation system cross sectional view:

This system consists of a carburetor mounted switch vent solenoid (SVS), Fig. 1, and prevents carburetor fuel bowl vapors from being discharged into the atmosphere. When the engine is stopped, the SVS directs fuel bowl vapors into the EEC system vapor storage canister where they remain until the canister is purged. During normal engine operation, the SVS directs fuel bowl vapors into the inner vent tube, Fig. 1, where they are drawn into the intake air stream and burned. The SVS receives operating signals from the ignition switch and the Computer Controlled Emission Control System ECM.

Fig. 2 Checking switch vent solenoid:

1985 - 86 Testing

SWITCH VENT SOLENOID
1. Disconnect canister hose from bowl vent (C) nozzle of the storage canister, Fig. 2, and connect new hose to pipe leading to solenoid.
2. Blow air into test hose with ignition switch in both on and off positions. Air should pass through hose in both tests.
3. Start engine and allow to idle, then blow air through test hose. Air should not pass through solenoid.
4. If SVS fails to perform as outlined, check feed circuits from ECM and ignition switch and repair as needed. If feed circuits are satisfactory, SVS is defective.
5. Remove test hose and reconnect original hose to canister.