Checking Fuel Tank & Tank Venting System For Leaks With Tank Leakage Diagnosis Module (DM-TL) - Z4

Do not work with external pressurization as tank venting system will leak. Because of escaping fuel vapors, these tasks should only be carried out in well ventilated rooms or with a suitable extractor facility provided. Using BMW Diagnosis and Information System (DIS), go to FUNCTION AND COMPONENT SELECTION page by selecting: SERVICE FUNCTIONS, DRIVE, DIGITAL MOTOR ELECTRONICS, ACTIVATION DMTL PUMP and ADOPT TEST MODULE in test schedule. Switch to test schedule and implement ACTIVATION DMTL PUMP TEST MODULE VENTING. See Fig 1-Fig 4 .

Fig 1: Identifying Z4 Fuel System (1 Of 4)
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Fig 2: Identifying Z4 Fuel System (2 Of 4)
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Fig 3: Identifying Z4 Fuel System (3 Of 4)
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Fig 4: Identifying Z4 Fuel System (4 Of 4)
Courtesy of BMW OF NORTH AMERICA, INC.
Tank leak diagnosis pump pressurizes fuel tank and tank venting system. Carry out leak test. Terminate test module after completing leak test. Tank leak diagnosis pump will automatically shut down after about 15 minutes due to risk of overheating. Allow pump to cool down for at least 15 minutes, then continue procedure. Leak test can be carried out with a leak detector. Follow manufacturer's operating instructions. Possible causes of leaks are:
- Tank cap leaking. See FUEL CAP PRESSURE RELIEF VALVE TEST under FUEL EVAPORATION.
- Tank vent line leaking (fuel tank-carbon canister).
- Tank vent line leaking (engine compartment).
- Sealing ring on fuel filter leaking.