Evaporative Emissions System: Testing and Inspection

FUEL TANK BREATHER. CHECKING

Special tools, testers and auxiliary items
- Hand vacuum pump VAG 1390
- Vacuum tester VAG 1368

Test conditions
- Ignition switched off

Test sequence
- Remove air cleaner.





- Pull breather hose -1- to regulator valve -6- off throttle valve housing -2-. Connect VAG 1390 hand vacuum pump to hose -1-.
- Remove breather hose -3- from fuel tank, from EVAP canister -4- and connect to connection -A- of VAG 1368 vacuum tester.
- Connect VAG 1368 vacuum tester connection -B- to EVAP canister.
- Set vacuum tester to position -B-.
- Operate hand VAG 1390 vacuum pump several times.

- Vacuum must not build-up

If vacuum builds-up:
- Check EVAP canister connection for clogging, and clean if necessary.
- Check EVAP canister purge regulator valve -N80- -6- for continuity, and replace if necessary.

If vacuum does not build-up:
- Remove fuel tank filler cap.





- Connect VAG 1390 hand vacuum pump to VAG 1368 vacuum tester connection -B-.
- Set vacuum tester to A/B position.
- Operate VAG 1390 several times.
- Vacuum must not build-up

If vacuum builds-up:
- Check gravity valve, refer to the item 28 in "Fuel Filter and Fuel Tank With Attaching Parts, Replacing". Service and Repair
- Check line -3- from fuel tank for blockage.

If vacuum does not build-up:
- Reinstall fuel tank filler cap.
- Operate hand vacuum pump VAG 1390 several times.
- Vacuum must not build-up

NOTE: If the fuel level in the tank is low, hand vacuum pump may need to be operated at least 20-30 times.

If vacuum builds-up:
- Replace fuel tank cap.