Fuel System, Checking For Leaks

Fuel System (Engine Code BPY), Checking For Leaks

Special tools, testers and auxiliary items required







- Hose Clamps Up to 25 mm dia. 3094







- Tester V.A.G 1371

Test conditions:
- Ignition switched off.
- A leak was detected by Leak Detection Pump (LDP) V144.

- Remove right rear wheel and wheel housing liner.







- Clamp hose - arrow - closed between Leak Detection Pump (LDP) V144 and air filter using a Hose Clamps Up to 25 mm dia. 3094.







- Connect tester V.A.G 1371 as shown between Evaporative Emission (EVAP) Canister Purge Regulator Valve N80 - arrow - and vent line.
- Connect valve attachment of tester V.A.G 1371 to tire valve.
- Using valve - A -, regulate pressure to 35 mbar. After pressure has stabilized, it must not drop below 30 mbar for next 5 minutes.

If pressure does not build up or if positive pressure is not maintained for at least 5 minutes, locate leak as follows:
- Perform visual inspection at all components and hoses of fuel supply system.

NOTE: Also check sealing cap of fuel tank for leaks.

Only when up to now no malfunction has been detected:
- First check Evaporative Emission (EVAP) Canister Purge Regulator Valve N80 for leaks. To do so, clamp hose closed between Evaporative Emission (EVAP) Canister Purge Regulator Valve N80 and tester V.A.G 1371 using a hose clamp.

Repeat pressure test.
- If pressure now no longer falls, replace Evaporative Emission (EVAP) Canister Purge Regulator Valve N80.

If pressure still drops:







- Now check vent line, Leak Detection Pump (LDP) V144 and EVAP canister for leaks. To do so, disconnect vent line - A - from EVAP canister and seal connection using a plug - B -.
- Repeat pressure test.

If pressure still drops:







- With valve - A - opened, check the following lines and components for leaking areas by listening, touch, using standard leak detection spray or using ultrasonic measuring device V.A.G 1842.
- Line from Evaporative Emission (EVAP) Canister Purge Regulator Valve N80 to EVAP canister.
- EVAP canister
- Hose from EVAP canister to Leak Detection Pump (LDP) V144
- Leak detection pump (LDP) V144

If pressure no longer falls now, search for leak on fuel tank.







- To do so, connect vent line - A - again to EVAP canister.







- With valve - A - opened, check fuel tank for leaking areas by listening, touch, using standard leak detection spray or using ultrasonic measuring device V.A.G 1842.
- To check sealing flange, rear seat bench or luggage compartment floor cover must be removed.

After completing work, perform a leak test with Leak Detection Pump (LDP) V144 "Guided Functions".

CAUTION: After completing work, check tire pressure.