Evaporative Emissions System: Testing and Inspection

Purge Valve Testing:

Purge Valve
1. Remove the purge valve.
2. Connect a suitable vacuum pump to the purge valve.
3. With a shop made jumper apply 12 volts across the valve terminals.
4. Apply 17 inHg vacuum (600 mbar) to the valve.
5. Turn the vacuum pump off.

The vacuum should not drop by more than 1.5 inHg (50 mbar) within 20 seconds.

6. Disconnect the 12 volt jumper.
7. Restart the vacuum pump.

Vacuum should not be present.

^ Replace the purge valve as necessary.

Charcoal Canister
1. Check the vapor lines at the canister for aging and damage. Replace as necessary.
2. Remove the purge valve.
3. Connect a suitable vacuum pump to the outlet hose of the charcoal canister.
4. Remove the inlet hose at the charcoal canister.
5. Operate the vacuum pump.

Air passages must be open and vacuum should not be present. If not:

^ Replace the canister if blocked.
^ Replace the canister if it is saturated with fuel; check the expansion tank, fuel tank, and lines for blockage or high pressure.

Vapor-Liquid And Vacuum System
Check all vapor-liquid hoses and connections for cracking, restrictions and poor connections. The fuel tank, expansion tank and fuel cap must be free from leaks. Repair/replace components as necessary.