Volkswagen Workshop Service and Repair Manuals > Golf Mk4 > Power unit | 4-cyl. injection engine (natural gas) | Fuel supply, gas operation | Activated charcoal filter system

Checking fuel tank venting

Special tools and workshop equipment required

t	Vacuum tester -V.A.G 1368-

t	Hand vacuum pump -VAS 6213-

Test procedure

–	Remove fuel filler cap from filler neck.

–	Connect hand vacuum pump -VAS 6213- to vacuum tester -V.A.G 1368- -connection B-.

–	Set vacuum tester -V.A.G 1368- to -A/B- position.

–	Operate hand vacuum pump -VAS 6213- several times. Vacuum must not build up.

If vacuum builds up:

–	Check gravity valve → Item.

–	Check line -1- from fuel tank for blockage.

If vacuum does not build up:

–	Refit fuel filler cap.

–	Operate hand vacuum pump -VAS 6213- several times. Vacuum must not build up.

Note

If the fuel level in the tank is low the hand vacuum pump must be operated at least 20...30 times.

If vacuum builds up:

–	Renew fuel tank cap.

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