Delivery Quantity, Checking
- Voltage supply is OK.
- The fuel pressure regulator and residual pressure is OK. Refer to FUEL PRESSURE REGULATOR AND RESIDUAL PRESSURE, CHECKING .
- The fuel filter is OK.
-- Remove the fuel cap from the fuel filler tube.
-- Remove the rear bench seat. Refer to Removal and Installation .
-- Remove the cover -1- from fuel delivery unit. The arrow -2- points in the direction of travel.
-- First, pull on the connector -arrow- without pressing the retainer to make sure it connected securely. If the connector was not connected correctly, it could cause a fault.
-- Disconnect the connector.
-- Check the contacts on the connector and the fuel delivery unit for damage.
-- Install the test instrument adapter/DSO (5-pin) VAS 5565 between the connectors on the fuel delivery unit and cover.
-- Connect the remote control V.A.G 1348/3A to the test instrument adapter/DSO (5-pin) VAS 5565 and to battery positive (+).
This step allows the fuel pump to run when the engine is not running.
The delivery rate of the fuel pump is measured at 4 bar. Therefore, measure the fuel pressure before measuring the delivery rate. Refer to FUEL PRESSURE REGULATOR AND RESIDUAL PRESSURE, CHECKING .
The fuel system is under pressure!
- Always wear protective eyewear and protective clothing to prevent injuries and fuel from coming in contact with your skin.
- Before loosening line connections, place a cloth around the connection point. Then release pressure by carefully pulling off the line.
-- Disconnect the return line -1- from the fuel pressure regulator.
Press in the securing ring to disengage the fuel line.
-- the adapter VAS 6550/1 to the fuel pressure regulator and hold the other end of the adapter in a measuring container.
-- Operate the remote control V.A.G 1348/3A approximately 5 seconds in order to fill the fuel filter.
-- Empty the measuring container.
-- The fuel pump delivery rate depends on the voltage. So, connect the multi-meter V.A.G 1715 to wires -1 and 5- on the test instrument adapter/DSO (5-pin) VAS 5565.
-- Operate the remote control for 60 seconds and simultaneously measure the voltage of the fuel pump.
-- Compare the quantity of fuel delivered with the specification.
*) Minimum delivery rate cm3 /60 s
**) Voltage of the fuel pump with engine running in idle and the pump is on.
Example:
During the test, a voltage of 10.5 volts is measured. This results in a minimum delivery quantity of approximately 1200 cm3 /60 s.
If the minimum delivery rate is not attained:
-- Check the fuel filter as follows:
The fuel system is under pressure!
- Always wear protective eyewear and protective clothing to prevent injuries and fuel from coming in contact with your skin.
- Before loosening line connections, place a cloth around the connection point. Then release pressure by carefully pulling off the line.
-- Disconnect the fuel supply line -arrow- from the fuel filter.
-- Connect the pressure tester VAS 6550 to the fuel supply line using the adapter VAS 6550/1. Hold the other end of adapter VAS 6550/2 in the measuring container.
-- Make sure the drain is closed and the shut off levers are open.
-- Operate the remote control V.A.G 1348/3A. Slowly close the shut off lever -A- until the pressure gauge reads 4 bar. From this point on do not move the position of the shut off lever.
-- Empty the measuring container.
-- Repeat the fuel delivery test.
If the minimum delivery rate is now obtained:
-- Replace the fuel filter.
If the minimum delivery rate is again not obtained:
-- Remove the fuel delivery unit and check the fuel strainer for contamination.
Only when up to now no malfunction has been detected:
-- Replace the fuel delivery unit. Refer to FUEL DELIVERY UNIT .
-- Reconnect all disconnected fuel lines.
-- Bleed the fuel supply system. Refer to FUEL SYSTEM, BLEEDING .
Delivery rate has been obtained, but malfunctions are still suspected in the fuel supply, for example sporadic loss of fuel supply:
-- Check the fuel pump current draw. Refer to CURRENT DRAW, CHECKING .