16 00 510 Conducting leak test on fuel tank and tank ventilation system

NOTE: Charge fuel tank and tank ventilation system with pressure, refer to 16 00 100 CHECKING FUEL TANK AND TANK VENTILATION SYSTEM FOR LEAK-TIGHTNESS

CAUTION: Escaping fuel vapors; only work in well ventilated rooms or use suitable exhaust extraction unit.

Observe country-specific accident prevention and occupational safety regulations.

The leak test can be carried out with a leak detector.

Fig 1: Identifying Leak Detector

Possible causes may be:

Fuel filler cap leaky.
Tank ventilation lines leaky (fuel tank activated carbon canister tank ventilation valve).
Tank ventilation valve leaky (engine compartment).
Tank sensor on fuel tank leaky.
Activated carbon canister non-return valve leaky (spare wheel recess).

To make sure that the tank venting valve (engine compartment) does not leak, carry out the following work steps.

Detach scavenging air line (1) and disconnect from tank venting valve.

Fig 2: Detaching Scavenging Air Line

Seal scavenging air line with special tool 16 1 162.

Fig 3: Sealing Scavenging Air Line

Carry out another leak test as described above.

If no further leaks can be detected, the tank venting valve is leaking and must be replaced.

If the system continues to leak, carry out a leak test.