Fuel System, Checking For Proper Seal

Fuel System, Checking For Proper Seal

- A leak was recognized by the Leak Detection Pump (LDP) V144.
- Remove left rear wheel and wheelhousing liner.







- Clamp the hose - A - shut between the Leak Detection Pump (LDP) V144 and the air filter using a Hose Clamps up to 40mm 3093.







- Connect the Test Unit for K-Jetronic V.A.G 1371 between Evaporative Emission (EVAP) Canister Purge Regulator Valve N80 and the breather line, as shown.
- Connect the valve connector from Test Unit for K-Jetronic V.A.G 1371 to tire valve.
- Using the valve - A -, regulate the pressure to 35 mbar. After the pressure has stabilized, it must not drop below 30 mbar for the next 5 minutes.

If there is no pressure or the pressure does not hold for 5 minutes, the leak is to be located as follows:
- Using a Hose Clamps up to 40 mm, clamp shut the breather line between Evaporative Emission (EVAP) Canister Purge Regulator Valve N80 and engine.
Repeat the pressure test.
- If the pressure no longer falls, replace the Evaporative Emission (EVAP) Canister Purge Regulator Valve N80.

If the pressure drops again:
- Perform a visual inspection on all fuel system components and hoses.

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

Only when up to now no malfunction has been detected:
- Remove cover for EVAP canister.







- Pull breather line from fuel tank off from EVAP canister and plug the connection - A -. Repeat the pressure test.

If the pressure drops again:







- Open valve - A - on Test Unit for K-Jetronic V.A.G 1371.
- Check the following lines and components for poorly sealed areas by listening, feeling, using commercially available leak detection spray or by using the Ultrasonic Measuring Device V.A.G 1842.

- Line from Evaporative Emission (EVAP) Canister Purge Regulator Valve N80 to EVAP canister.
- EVAP canister
- Line from EVAP canister to Leak Detection Pump (LDP) V144.
- Leak Detection Pump (LDP) V144







NOTE: By clamping off the breather line above the rear axle, the leaking area can be isolated.

If pressure no longer falls, search for a leak at the fuel tank.
- When doing this, connect the breather line to the EVAP canister again.







- Open valve - A - on Test Unit for K-Jetronic V.A.G 1371.
- Now check the fuel tank for poorly sealed areas by listening, feeling, using commercially available leak detection spray or by using the Ultrasonic Measuring Device V.A.G 1842.
- To check the connections at the fuel filler tube, remove the right rear wheel housing liner.
- To check the sealing flange, remove the rear seat bench and the luggage compartment floor covering.
After completing work, perform a leak test with the Leak Detection Pump (LDP) V144 via "Guided Functions".

CAUTION: After completing work, check tire pressure.