Evaporative Emission Control System Testing

Evaporative Emission Control System:

THERMOSTATIC VACUUM SWITCH (TVS) TESTING

1. Start test with cold engine (coolant temperature below 46°C, 115°F).
2. Remove both hoses from TVS and plug. Check that no air passes between the TVS ports.
3. Attach a hose to either TVS port and warm up engine. Blow on the hose and check that air passes between the TVS ports when the specified temperature is surpassed.
4. As an alternative, a similar test can be run with TVS removed from vehicle and heated in a pan of water.
5. Replace TVS if found defective.

CANISTER VISUAL CHECK

1. Replace canister if cracked or otherwise damaged.
2. Replace canister if fuel is leaking from the bottom.
3. If dirty, plugged or damaged, replace filter at bottom of canister.

FUEL VAPOR LINES, FUEL TANK AND FILLER CAP INSPECTION

1. Visually inspect lines and connections for looseness, kinked or collapsed hoses or other damage.
2. Visually inspect fuel tank and filler cap for deformation, cracks or fuel leakage.
3. Repair or replace any components found to be damaged or defective.