Fuel Delivery Rate, Checking, Vehicles Without Fuel Pump Control Module -J538-
Special Tools And Workshop Equipment Required
- Trim Removal Wedge 3409
- Injection Rate Comparison Meter Kit - Remote Cable VAG 1348/3A
- Multimeter, for example Analog/Digital Multimeter FLU 83III
- Vehicle Diagnostic Tester - Test Adapter - 5 Pin VAS 5565
- Pressure Tester Kit VAS 6550
- Pressure Regulator Valve VAS 6550/4
- Vehicle Diagnostic Tester
- Measuring Container, Three Liter
If driving is still impaired with the fuel tank a maximum of 1 /4 full, then perform a fuel delivery test with the fuel tank only 1 /4 full or with very little fuel in the fuel tank.
Test Conditions
- Voltage supply OK. Refer to FUEL PUMPS, CHECKING FUNCTION AND POWER SUPPLY .
- Fuel pressure OK. Refer to FUEL PRESSURE, CHECKING .
- The battery voltage must be at least 11.5 V. Charge if necessary. Refer to DESCRIPTION AND OPERATION .
- Fuel Pump Control Module -J538- fuse OK. Refer to appropriate Wiring Diagram.
- Fuel Pump Control Module -J538- is OK see Vehicle Diagnostic Tester.
- Fuel Pump Relay -J17- OK see Vehicle Diagnostic Tester.
- Fuel pump fuse OK. Refer to appropriate Wiring Diagram
- Pull on the connector without pressing the release to make sure the connection is secure. Repeat the fuel pump functionality test if the connector was not connected correctly.
- Fuel level inside the fuel tank is above reserve
Test Sequence
Follow the guidelines for clean working conditions. Refer to PARKING/AUXILIARY HEATER AND FUEL SYSTEM CLEAN WORKING CONDITIONS .
Follow all safety precautions. Refer to SAFETY PRECAUTIONS .
Checking the Fuel Delivery Rate in the Engine Compartment
-- Remove the rear bench seat. Refer to REMOVAL AND INSTALLATION .
-- Unclip the cover -1- at the tabs -arrows- using the Trim Removal Wedge 3409.
-- Pull on the connector -arrow- without pressing the release to make sure the connection is secure.
If the connector was not connected correctly, it could cause a fault.
-- Disconnect the connector -arrow-.
-- Check the contacts on the connector and on the fuel delivery unit for damage.
-- Attach the Vehicle Diagnostic Tester - Test Adapter - 5 Pin VAS 5565 to the connector and to the fuel delivery unit.
-- Connect the Injection Rate Comparison Meter Kit - Remote Cable VAG 1348/3A to the Vehicle Diagnostic Tester - Test Adapter - 5 Pin VAS 5565 and the battery positive terminal clamp in the engine compartment.
This work step allows the fuel pump to run when the engine is not running.
-- Fuel delivery rate of the fuel pump is dependent on battery voltage. Also connect the Multimeter VAG 1526E to the wires -1 and 5- in the Vehicle Diagnostic Tester - Test Adapter - 5 Pin VAS 5565.
-- Remove the supply line -1-. Disconnect the connector couplings. Refer to CONNECTOR COUPLINGS, SEPARATING .
-- Wipe up any leaking fuel with a cloth.
-- Connect the Pressure Tester Kit - Hose 1 VAS 6550/1 to the connection -A- on the Pressure Tester Kit VAS 6550.
-- Connect the Pressure Regulator Valve VAS 6550/4 to the Pressure Tester Kit VAS 6550 connection -B-.
-- Connect the Pressure Tester Kit - Hose 2 VAS 6550/2 to the fuel line from the fuel tank.
-- Hold the open end of the Pressure Regulator Valve VAS 6550/4 hose in a measuring container.
-- Pull on the connector couplings to make sure they are secure.
-- Make sure that the drain valve -C- on the Pressure Tester (Diesel) -1- is shut.
-- The shut-off valves -A and B- on the Pressure Tester Kit -1- are opened.
-- Push the Injection Rate Comparison Meter Kit - Remote Cable VAG 1348/3A.
The Transfer Fuel Pump -G6- is activated!
-- Adjust the pressure to 4 bar (58 psi) with the adjustment wheel on the Pressure Regulator Valve VAS 6550/4 -arrow-.
-- From this point on do not move the pressure setting knob.
-- Empty measuring container.
-- Press the remote control for 60 seconds while measuring the battery voltage.
-- Compare the delivered quantity of fuel with the specified value in the table.
Example
During test, a voltage of 10.5 Volts is measured. This results in a minimum delivery quantity of approximately 1200 cm3 /60 s.
If Specification Is Not Obtained
-- Open the fuel filler door unit.
-- Clean the area around the fuel filler tube.
-- Remove the cap -arrow- for the fuel filler tube.
-- Check the fuel delivery rate again. Refer to FUEL TANK, CHECKING VENTILATION .
If Specified Value Is Achieved
-- Check the fuel tank ventilation.
If the Specification Is Not Obtained
-- Check the fuel lines for possible restrictions (kinks) or blockages.
-- Check the fuel lines for leaks and damage.
If No Malfunction Can Be Found
Proceed as follows to check the fuel delivery rate to the fuel filter.
Checking the Fuel Delivery Rate to the Fuel Filter
-- Disconnect the fuel supply line -arrow- from the fuel filter. Disconnect the connector couplings. Refer to CONNECTOR COUPLINGS, SEPARATING .
-- Connect the Pressure Tester Kit - Hose 1 VAS 6550/1 to the connection -A- on the Pressure Tester Kit VAS 6550.
-- Connect the Pressure Regulator Valve VAS 6550/4 to the connection -B- on the Pressure Tester Kit VAS 6550.
-- Connect the Pressure Tester kit VAS 6550 to the fuel supply line -2- with the Pressure Tester Kit - Hose 2 VAS 6550/2.
-- Hold the open end of the Pressure Regulator Valve VAS 6550/4 hose in a measuring container.
-- Make sure that the drain valve -C- on the Pressure Tester (Diesel) -1- is shut.
-- The shut-off valves -A and B- on the Pressure Tester Kit -1- are opened.
-- Push the Injection Rate Comparison Meter Kit - Remote Cable VAG 1348/3A.
The Transfer Fuel Pump -G6- is activated!
-- Adjust the pressure to 4 bar (58 psi) with the adjustment wheel on the Pressure Regulator Valve VAS 6550/4 -arrow-.
-- From this point on do not move the pressure setting knob.
-- Empty measuring container.
-- Press the remote control for 60 seconds while measuring the battery voltage.
If Specified Value Is Achieved
-- Check the fuel line to the engine for possible kinks or blockages.
-- Check the fuel line to the engine for leaks and damage.
If No Fault Was Detected
-- Replace the fuel filter. Refer to FUEL FILTER .
If the Specification Is Not Obtained
Proceed as follows to check the fuel delivery rate at the fuel delivery unit:
Check the Fuel Delivery Quantity at the Fuel Delivery Unit
-- Pull the fuel line -1- off the flange. Disconnect the connector couplings. Refer to CONNECTOR COUPLINGS, SEPARATING .
-- Connect the Pressure Tester Kit - Hose 2 VAS 6550/2 to the connection -A- on the Pressure Tester Kit VAS 6550.
-- Connect the Pressure Regulator Valve VAS 6550/4 to the connection -B- on the Pressure Tester Kit VAS 6550.
-- Connect the Pressure Tester Kit VAS 6550 to the fuel delivery unit -1- with the Pressure Tester Kit - Hose 2 VAS 6550/2.
-- Hold the open end of the Pressure Regulator Valve VAS 6550/4 hose in a measuring container.
-- Make sure that the drain valve -C- on the Pressure Tester (Diesel) -1- is shut.
-- The shut-off valves -A and B- on the Pressure Tester Kit -1- are opened.
-- Push the Injection Rate Comparison Meter Kit - Remote Cable VAG 1348/3A.
The Transfer Fuel Pump -G6- is activated!
-- Adjust the pressure to 4 bar (58 psi) with the adjustment wheel on the Pressure Regulator Valve VAS 6550/4 -arrow-.
-- From this point on do not move the pressure setting knob.
-- Empty measuring container.
-- Press the remote control for 60 seconds while measuring the battery voltage.
If the Specification Is Not Obtained
-- Remove the fuel delivery unit. Refer to FUEL DELIVERY UNIT .
-- Check the fuel lines for possible restrictions (kinks) or blockages.
-- Remove the fuel delivery unit and check the filter screen for dirt.
-- Check the fuel lines for leaks and damage.
-- Check whether the hose connections -arrows- to the fuel delivery unit -1- are sealed.
If No Fault was Detected
-- Check the current draw of the fuel pump. Refer to CURRENT DRAW, CHECKING .
If No Faults were Found While Checking the Current Draw
-- Replace the fuel delivery unit. Refer to FUEL DELIVERY UNIT .
If the fuel delivery rate was reach, even though a fault in the fuel supply is still suspected (for example, intermittent loss of fuel supply):
-- Check the current draw of the fuel pump. Refer to CURRENT DRAW, CHECKING .
Tightening Specifications