Evaporative Emissions System: Testing and Inspection

CHECKING EVAP SYSTEM





Checking Ventilation Hose
^ Disconnect ventilation and vacuum hoses from Throttle Body.
^ Connect vacuum pump to ventilation hose (heavy hose) and pump up vacuum.

Gauge should indicate vacuum while pumping. Although pressure will revert quickly to atmospheric, distinct resistance should be felt while pumping.

If vacuum and resistance are present:
- Check vacuum hose.
If vacuum or resistance are not present:
- Check ventilation hose to carbon filter (canister) for damage or leakage.
If ventilation hose is intact:
- Try with new filter.





Checking vacuum hose
^ Connect pump to vacuum hose (light hose) and pump up vacuum.

Gauge should indicate vacuum.

If vacuum is present:
- Check EVAP valve.
If vacuum is not present:
- Check vacuum hose to carbon filter for damage or leakage.
If vacuum hose is intact:
- Try with new filter.





Checking EVAP Valve
^ Maintain vacuum in vacuum hose.
^ Blow through ventilation hose (heavy hose).

Carbon filter should pass air with some resistance when hose is blown through.

If filter passes air:
- Filter and EVAP valve are intact.
- Resume fault tracing at point of interruption.
If filter does not pass air:
- Check if vacuum hose is pinched.
If hose is intact:
- Try with new filter.