Pickup 2WD L4-2254cc 2.3L SOHC (4ZD1) MFI (1994)
Thermal Vacuum Valve - EVAP: Testing and Inspection
1. Apply battery voltage (12 volts DC) to the vacuum switching valve.
2. Check to see that air does not flow freely through (Y) and (Z) and flows freely through (X) and (Y).
3. Remove the voltage from the V.S.V.
4. Check to see that air flows freely through (Y) and (Z) and does not flow through (X) and (Y).
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If a problem is found, replace the V.S.V.
The roll over & float valves are designed to prevent fuel leaks when the vehicle has turned over. The relief valve is intended to relieve the tank
internal pressure to avoid tank damage when the pressure has reached a certain level as the result of the roll over & float valves blocking the fuel
escape. None of these components are relevant to the evaporative emission system.