Fuel Pressure And Residual Pressure Before High Pressure Pump, Checking
Special tools and workshop equipment required
- Fuel Inj. Pressure Gauge-CIS VAG 1318
- Pressure Gauge Adapter VAG 1318/10-12
- Connector Test Set VAG 1594C
- Remote Control VAG 1348/3A with Remote Control VAG 1348/3-3
- Measuring container, fuel-resistant
- Protective gloves
Fuel Pressure, Checking
- Battery voltage at least 12.5 Volts.
- Fuel filter OK.
- Fuel tank at least 1 /4 filled.
- Fuel Pump (FP) Control Module -J538- OK.
- Ignition switched off.
Fuel Pressure, Checking
-- Remove rear seat bench. Refer to SEAT BENCH/SINGLE SEAT, REMOVING AND INSTALLING .
-- Remove the locking flange cover -arrows-.
-- Disconnect electrical harness connector -1- at locking flange.
Ignore -2-.
-- Connect the VAG 1348/3A with VAG 1348/3-3 with an adapter cable from the VAG 1594C at terminal -1-.
-- Using insulating tape, tape over the second terminal on the VAG 1348/3-3 -arrow- to prevent a short circuit.
-- Connect terminal -5- to the vehicle ground using a jumper cable from the VAG 1594C.
-- Connect the VAG 1348/3A to item -A- in the terminal box in the plenum chamber (battery positive). For safety reasons, install a fuse (10 A) in the wiring connection.
-- Route VAG 1348/3A switch forward in engine compartment.
-- Remove the seal -arrow-.
-- Unclip the plenum chamber cover -2- and remove it.
Ignore -1 and 3-.
-- Release the retainer -arrow A- and open the cover -arrow B-.
-- Connect the VAG 1348/3A to item -A- in the terminal box in the plenum chamber (battery positive). For safety reasons, install a fuse (10 A) in the wiring connection.
-- Remove fuel filler cap from fuel filler tube.
-- Remove the front engine cover.
-- Remove the fuel supply line -arrow- from the high pressure pump.
There is a risk of injury because the fuel is under high pressure.
- To reduce pressure in fuel system, lay a clean cloth around the connector and carefully loosen connector.
-- Connect the VAG 1318 to the fuel supply line using an adapter.
-- Connect an assisting hose -arrow- to pressure gauge and hold it in a measuring container.
-- Open shut-off valve of pressure gauge.
- The lever points in the direction of flow.
-- Bleed fuel system by pressing remote control briefly.
-- Close shut-off valve of pressure gauge.
- Lever stands perpendicular to direction of flow -arrow-.
-- Hold the switch of the remote control until no more pressure increase is observed on the fuel pressure gauge.
- Specified value: approximately 5.5 bar (4.5 to 6.5 bar) positive pressure.
If the specification is not obtained:
-- Check the fuel pump delivery quantity. Refer to Transfer Fuel Pump -G6-, CHECKING .
Residual Pressure, Checking
-- Check for leaks and residual pressure by observing pressure drop on pressure gauge.
- After 10 minutes there must be a residual pressure of at least 3.75 bar.
If the residual pressure drops below 3.75 bar:
- Check connection between fuel pressure gauge and fuel line for leaks.
- Check pressure gauge for leaks.
- Check fuel lines and their connections for leaks.
- Check the fuel pump delivery quantity. Refer to Transfer Fuel Pump -G6-, CHECKING .
- Replace the fuel filter with the integrated fuel pressure regulator. Refer to FUEL FILTER, REMOVING AND INSTALLING .
- Fuel pump check-valve is faulty. Refer to FUEL DELIVERY UNIT/FUEL LEVEL SENSOR, REMOVING AND INSTALLING .
Assembly is performed in the reverse order of removal, noting the following:
-- Switch off ignition.
Before removing pressure gauge, release fuel pressure by opening shut-off valve. Hold a container under the connection.
-- Connect the fuel supply line -arrow- to the high pressure pump.
Check fuel system for leaks.