Checking the Fuel Delivery Rate Inside the Engine Compartment, Quick Test:
The fuel delivery rate is first checked in the engine compartment with the "Check fuel delivery rate, quick test" Guided Function. Perform a second measurement on the fuel delivery unit flange if the minimum delivery rate is not attained.
-- Connect the Vehicle Diagnostic Tester.
-- Start Guided Functions.
-- Check the fuel delivery rate function and select the quick test.
-- Follow the instructions displayed on the Vehicle Diagnostic Tester.
If the Specified Value Is Not Obtained:
-- Open the fuel filler door unit -2-.
-- Clean the area around the fuel filler neck.
-- Remove the cap -1- for the fuel filler neck.
-- Repeat checking the fuel delivery rate, quick test. Refer to Checking the Fuel Delivery Rate Inside the Engine Compartment, Quick Test: .
If the Specified Value Is Not Obtained:
-- Check the fuel tank ventilation. Refer to FUEL TANK, CHECKING VENTILATION .
If the Specified Value Is Not Obtained:
-- Check the fuel lines for possible restrictions (kinks) or blockages.
-- Check the fuel lines for leaks and damage.
If No Error Can Be Found:
Check the fuel delivery rate on the fuel delivery unit as follows:
Fuel Delivery Rate, Checking on Fuel Delivery Unit:
Disconnect the connector couplings. Refer to CONNECTOR COUPLINGS, DISCONNECTING .
If driving is still impaired with the fuel tank 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.
- Voltage supply OK. Refer to FUEL PUMPS, CHECKING FUNCTION AND POWER SUPPLY .
- Tension minimum 12 V.
- Fuel pressure is OK. Refer to FUEL PRESSURE, CHECKING .
- Fuel Pump Control Module -J538- is OK use the Vehicle Diagnostic Tester.
-- Connect the battery charger. Refer to BATTERY, CHARGING .
-- Remove the installation opening cover. Refer to FUEL DELIVERY UNIT COVER, REMOVING AND INSTALLING .
-- Remove the Fuel Pump Control Module -J538- with the connected wiring harness. Refer to Fuel Pump Control Module -J538-, REMOVING AND INSTALLING .
-- Remove the Fuel Pump Control Module -J538- toward the inside between the fuel tank and the floor panel.
-- Move the Fuel Pump Control Module -J538- together with the wiring harness to the side.
-- 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.
-- Release and disconnect the connector.
-- Check the contacts on the connector and on the fuel delivery unit for damage.
-- Connect the :VAS5565 -E- to the fuel delivery unit -A-.
-- Connect the :VAG1348/3A -D- to the :VAS5565 and the battery positive terminal clamp -B- in the engine compartment.
-- Connect the connection -5- (yellow) on the :VAS5565 to the battery negative terminal -B- using suitable service equipment -C-.
-- To do so, use the :VAG1594D also.
-- The fuel pump delivery rate is dependent on the battery voltage. Connect the :FLUKE83III to the connectors -1- (red) and -5- of the :VAS5565 .
-- Connect the :FLUKE83III with the :VAG1594D .
This step allows the fuel pump to run when the engine is not running.
The fuel system is under pressure.
Risk of injury from fuel spraying out.
- Wear protective eyewear.
- Wear safety gloves.
- Reduce the pressure: place clean cloths around the connection point and carefully open the connection point.
-- Remove the supply line -1-. Disconnect the connector couplings. Refer to CONNECTOR COUPLINGS, DISCONNECTING .
-- Collect leaking fuel with a cleaning cloth.
-- Connect the :VAS6550/2 -2- to the connection -A- on the :VAS6550 -1-.
-- Connect the :VAS6550/4 -3- to the connection -B- on the :VAS6550 -1-.
-- Hold the open end of the :VAS6550/4 -3- hose in a measuring container -4-. Have a second technician hold the measuring container and hose so they are secure.
Risk of a fire due to leaking fuel.
Severe injuries and burns are possible.
- Before the test, check if all connected lines are securely connected by pulling on them.
- Remove any cleaning cloths soaked in fuel from the vehicle area.
- Place the measuring container outside of the vehicle and make sure it is securely positioned.
- With the help of a second technician, make sure the end of the hose stays in the measuring container and the measuring container does not tip over during the test.
-- Make sure that the drain valve -C- on the :VAS6550 -1- is closed.
-- The shut-off valves -A and B- on the :VAS6550 -1- are opened.
-- Push the :VAG1348/3A .
The Transfer Fuel Pump -G6- is activated!
-- Adjust the pressure to 4.0 bar (58.01 psi) with the adjustment wheel on the :VAS6550/4 -arrow-.
-- From this point on do not move the adjustment wheel.
-- Empty the measuring container.
-- Press the remote control for 60 seconds while measuring the fuel pump voltage.
-- Compare the delivered quantity of fuel with the specified value in the table.
| Axis Designation | Unit |
|---|---|
| Minimum delivery rate | cm3 |
| Fuel pump voltage when the engine is idling and the pump is running | Volt |
Example:
During test, a voltage of 10.5 Volts is measured. This results in a minimum delivery quantity of approximately 1500 cm3 /60 s.
If the Specified Value Is Not Obtained:
Proceed as follows to check the fuel delivery rate at the fuel delivery unit:
The fuel system is under pressure.
Risk of injury from fuel spraying out.
- Wear protective eyewear.
- Wear safety gloves.
- Reduce the pressure: place clean cloths around the connection point and carefully open the connection point.
-- Remove the fuel lines -1- from the flange. Disconnect the connector couplings. Refer to CONNECTOR COUPLINGS, DISCONNECTING .
-- Connect the :VAS6550 -1- to the fuel delivery unit using the :VAS6550/3-4 -2-.
-- Connect the :VAS6550/3-4 -2- to the connection -A- on the :VAS6550 -1-.
-- Connect the :VAS6550/4 -3- to the connection -B- on the :VAS6550 -A-.
-- Make sure all connected lines are securely in place by pulling on them.
-- Place the measuring container -4- outside of the vehicle and make sure it is securely positioned. Use suitable service equipment for this.
-- Have a second technician make sure it is securely positioned.
-- Hold the open end of the hose coming from the pressure regulating valve in a measuring container -4-.
-- Have a second technician ensure the end of the hose stays in the measuring container during the test.
-- Make sure that the drain valve -C- on the :VAS6550 -1- is closed.
-- The shut-off valves -A and B- on the :VAS6550 -1- are opened.
-- Push the :VAG1348/3A .
The Transfer Fuel Pump -G6- is activated!
-- Adjust the pressure to 4 bar (58.01 psi) with the adjustment wheel on the :VAS6550/4 -arrow-.
-- From this point on do not move the adjustment wheel.
-- Empty the measuring container.
-- Press the remote control for 60 seconds while measuring the fuel pump voltage.
-- Compare the delivered quantity of fuel with the specified value in the table.
| Axis Designation | Unit |
|---|---|
| Minimum delivery rate | cm3 |
| Fuel pump voltage when the engine is idling and the pump is running | Volt |
Example:
During test, a voltage of 10.5 Volts is measured. This results in a minimum delivery quantity of approximately 1500 cm3 /60 s.
If the Specified Value Is Obtained:
-- Check the fuel lines for possible restrictions (kinks) or blockages.
-- Check the fuel lines for leaks and damage.
If the Specified Value Is Not Obtained:
-- Remove the fuel delivery unit. Refer to FUEL DELIVERY UNIT/FUEL LEVEL SENSOR, REMOVING AND INSTALLING .
-- Check the filter screen for contaminants.
-- Check whether the hose connections -arrows- to the fuel delivery unit -1- are sealed.
-- Check the fuel lines for possible restrictions (kinks) or blockages.
-- Check the fuel lines for leaks and damage.
If No Malfunction Was Detected:
-- Replace the fuel delivery unit. Refer to FUEL DELIVERY UNIT/FUEL LEVEL SENSOR, REMOVING AND INSTALLING .