Fuel Delivery Rate, Checking Engine Codes CVCA
Special tools and workshop equipment required
- Diesel Pressure Tester KitVAS6551
- Diesel Pressure Tester Kit - Adapter Set VAS6551/5
- Trim Removal Wedge3409
- Hose Clip Pliers VAG1921
- Pressure Regulator ValveVAS6551/6
- Vehicle Diagnostic Tester
- Measuring Container, Minimum Capacity: 3 liters
Remember, the fuel pump will turn on when a door is opened, if the battery is connected. Fuel may leak out when the system is open.
Test Conditions:
- Connect the battery charger. The voltage must be minimum 12.5 V. Refer to BATTERY, CHARGING .
- Fuses OK; refer to the appropriate Wiring Diagram.
- Fuel Pump Control Module -J538- is OK, refer to Vehicle Diagnostic Tester.
- The fuel filter is OK.
- Fuel tank minimum 1 /2 full.
- Make sure the vehicle is level.
- All electrical consumers such as, for example, headlamps and rear window defogger, must be off.
- Fuel pressure OK. Refer to FUEL PRESSURE, CHECKING ENGINE CODES CVCA .
The vehicle must be fueled with diesel fuel treated for the season. Summer diesel fuel can coagulate at low winter temperatures under some conditions.
Diesel fuel bought in the summer can be filtered to 0 °C (32 °F).
Diesel fuel sold during the transition time can be filtered to -10 °C (14 °F).
Diesel fuel bought in the winter can be filtered to -20 °C (-4 °F).
Test a sample in the winter if there is doubt. The sample should set outside at low outside air temperature for approximately 1 hour. If the fuel coagulates at temperatures down to -20°C, then this diesel fuel is not suited for low temperatures. This coagulation can plug the screen in the fuel delivery unit as well as in the fuel filter.
-- Follow all safety precautions. Refer to SAFETY PRECAUTIONS .
-- Follow the guidelines for clean working conditions. Refer to PARKING/AUXILIARY HEATER AND FUEL SYSTEM CLEAN WORKING CONDITIONS .
-- Turn off the ignition.
-- Remove the engine cover. Refer to [ENGINE COVER .
-- Move the right front seat all the way forward.
-- Remove the rear bench seat. Refer to REAR SEATS .
-- Open the clamp -arrow- on the fuel supply line -1-.
Fuel lines are under pressure.
Danger of personal injury to eyes and skin.
Wear protective eyewear and protective clothing in order to avoid injury and contact with the skin. Wrap a cloth around the connection before loosening hose connections. Open the connection carefully and release the pressure.
-- Remove the fuel supply line -1- from the high pressure pump -2-.
-- Insert the Diesel Pressure Tester Kit - Adapter Set - Adapter 1VAS6551/5-1 into the fuel supply line and secure with a clamp.
-- Connect the Diesel Pressure Tester Kit - Hose 2VAS6551/2 between the Diesel Pressure Tester Kit - Adapter Set - Adapter 1VAS6551/5-1 and the connection -A- on the Diesel Pressure Tester KitVAS6551.
-- Connect the Pressure Regulator ValveVAS6551/6 to the connection -B- on the Diesel Pressure Tester KitVAS6551.
-- Hold the open end of the Pressure Regulator ValveVAS6551/6 hose in a measuring container.
-- Press the On/Off button to switch on the Diesel Pressure Tester KitVAS6551.
-- Make sure that the drain valve -C- on the Diesel Pressure Tester KitVAS6551 -1- is closed.
-- The shut-off valves -A- and -B- are opened on the Diesel Pressure Tester KitVAS6551 -1-.
-- Connect the Vehicle Diagnostic Tester.
-- Select Guided Function 01 activate fuel pump .
-- Select check fuel pump delivery pressure/delivery .
-- Follow the instructions given by the Vehicle Diagnostic Tester.
-- Set the pressure to 4.5 bar using the Pressure Regulator ValveVAS6551/6.
-- The initial pressure is set by turning the adjusting wheel -arrow- on the Pressure Regulator ValveVAS6551/6.
- Specified value: 4.6 bar pressure.
-- Do not move the adjusting wheel -arrow- any more.
-- Empty measuring container.
-- Repeat Check Fuel Pump Delivery Pressure/Delivery .
The Transfer Fuel Pump -G6- is now activated for 30 seconds.
-- Check the amount of fuel in the measuring container.
- Specified value: Minimum delivery rate 1, 100 cm3 /30 s.
If the minimum delivery rate is not attained:
-- Check the fuel lines inside the engine compartment for possible bends, blockages and damage.
-- Check the fuel lines inside the engine compartment for leaks.
If no malfunction can be found:
Check the fuel delivery quantity in front of the fuel filter as follows:
Check the fuel delivery quantity in front of the fuel filter:
-- Remove the supply line -B- and wipe up the draining fuel with a cleaning cloth. Disconnect the connector couplings. Refer to CONNECTOR COUPLINGS, SEPARATING .
Fuel lines are under pressure.
Danger of personal injury to eyes and skin.
Wear protective eyewear and protective clothing in order to avoid injury and contact with the skin. Wrap a cloth around the connection before loosening hose connections. Open the connection carefully and release the pressure.
-- Connect the Diesel Pressure Tester Kit - Hose 2VAS6551/2 to the fuel supply line coming from the fuel tank.
-- Connect the Diesel Pressure Tester Kit - Hose 2VAS6551/2 to the connection -A- on the Diesel Pressure Tester KitVAS6551.
-- Connect the Pressure Regulator ValveVAS6551/6 to the connection -B- on the Diesel Pressure Tester KitVAS6551.
-- Hold the open end of the Pressure Regulator ValveVAS6551/6 hose in a measuring container.
-- Press the On/Off button to switch on the Diesel Pressure Tester KitVAS6551.
-- Make sure that the drain valve -C- on the Diesel Pressure Tester KitVAS6551 -1- is closed.
-- The shut-off valves -A- and -B- are opened on the Diesel Pressure Tester KitVAS6551 -1-.
-- Repeat Check Fuel Pump Delivery Pressure/Delivery , refer to FUEL DELIVERY RATE, CHECKING ENGINE CODES CVCA => Connect the Vehicle Diagnostic Tester. .
If the minimum delivery rate is now obtained:
Check and fuel filter and replace it, if necessary. Refer to FUEL FILTER, REMOVING AND INSTALLING .
If specified value is again 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:
-- Remove the rear bench seat. Refer to REAR SEATS .
-- Unclip the cover -1- at the tabs -arrows- using the Trim Removal Wedge3409.
Remember, the fuel pump will turn on when a door is opened, if the battery is connected. Fuel may leak out when the system is open.
-- Remove the fuel return line -1- from the locking flange. Disconnect the connector couplings. Refer to CONNECTOR COUPLINGS, SEPARATING .
Fuel lines are under pressure.
Danger of personal injury to eyes and skin.
Wear protective eyewear and protective clothing in order to avoid injury and contact with the skin. Wrap a cloth around the connection before loosening hose connections. Open the connection carefully and release the pressure.
-- Connect the Diesel Pressure Tester Kit - Hose 2VAS6551/2 to the connection for the fuel supply line on the fuel delivery unit.
-- Connect the Diesel Pressure Tester Kit - Hose 2VAS6551/2 to the connection -A- on the Diesel Pressure Tester KitVAS6551.
-- Connect the Pressure Regulator ValveVAS6551/6 to the connection -B- on the Diesel Pressure Tester KitVAS6551.
-- Hold the open end of the Pressure Regulator ValveVAS6551/6 hose in a measuring container.
-- Press the On/Off button to switch on the Diesel Pressure Tester KitVAS6551.
-- Make sure that the drain valve -C- on the Diesel Pressure Tester KitVAS6551 -1- is closed.
-- The shut-off valves -A- and -B- are opened on the Diesel Pressure Tester KitVAS6551 -1-.
-- Repeat Check Fuel Pump Delivery Pressure/Delivery , refer to FUEL DELIVERY RATE, CHECKING ENGINE CODES CVCA => Connect the Vehicle Diagnostic Tester. .
If the minimum delivery rate is now obtained:
-- Check the fuel lines for possible bends, blockages and damage.
-- Check fuel lines for leaks.
If specified value is again not obtained:
-- Remove the fuel delivery unit. Refer to FUEL DELIVERY UNIT/FUEL LEVEL SENSOR, REMOVING AND INSTALLING .
-- Check the filter screen for dirt.
-- Make sure all the hoses are connected -arrows-.
Only when up to now no malfunction has been detected:
-- Replace the fuel delivery unit. Refer to FUEL DELIVERY UNIT/FUEL LEVEL SENSOR, REMOVING AND INSTALLING .