Fuel Delivery, Checking

WARNING: This page is about a different variant/trim than selected.

Special tools and workshop equipment required

Hand held remote control (jumper).
Multimeter.
Electrical connector test lead set.
Fuel pressure test set (high pressure).
Measuring container, fuel-resistant.

Test conditions

Battery voltage 12.5 V
Fuel filter OK
Fuel tank at least ¹ /₄ filled.
Fuel pressure regulator OK.
Ignition switched off.

WARNING:

Fuel supply line is under pressure! Wear protective goggles and protective clothing to prevent injuries and contact with skin. Before loosening hose connections, place rags around the connection point. Then release pressure by carefully pulling on hose.

Procedure

-- Remove fuel filler cap from fuel filler tube.

-- Remove the rear seat bench. Refer to Rear Seats .

-- Remove the cover -1- with Fuel Pump (FP) Control Module -J538- -2- from the fuel pump.

Fig 1: Identifying Cover With Fuel Pump Control Module J538

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Connect a Hand held remote control (jumper) to terminal -1- of the fuel delivery unit and to vehicle battery (+).

-- Connect a jumper cable from a Electrical connector test lead set to terminal -5- of the fuel delivery unit and to vehicle Ground (GND).

Fig 2: Identifying Jumper Cable From Electrical Test Lead Set Connected To Fuel Delivery Unit Terminal And Vehicle Ground

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

WARNING:

-- Disconnect the fuel supply line -2- and catch escaping fuel using a rag.

Fig 3: Identifying Fuel Supply Line

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

NOTE:

Press in securing ring to disengage the fuel lines.

-- Connect a High pressure fuel gauge between the fuel filter and fuel supply line.

Fig 4: Identifying High Pressure Fuel Gauge Connected Between Fuel Filter And Fuel Supply Line

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Connect a fuel line from the High pressure fuel gauge to the disconnected fuel return line and hold it in the measuring container.

Fig 5: Identifying Fuel Line From High Pressure Fuel Gauge Connected To Fuel Return Line And Held In Measuring Container

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

WARNING:

Danger of spraying when opening shut-off valve; wear protective goggles and protective clothing to prevent injuries and contact with skin. Hold container in front of open connection of pressure measuring device.

-- Close the shut-off valve of High pressure fuel gauge.

-- Press switch on the Hand held remote control (jumper) while opening the shut-off valve slowly until 4 bar positive pressure is indicated on pressure gauge. Do not change position of the shut-off valve.

-- Empty into the measuring container.

Delivery rate of the fuel pump is dependent on the battery voltage.

-- Operate the remote control for 30 seconds.

-- Using a Multimeter, check battery voltage while the fuel pump is running.

-- Compare the fuel quantity pumped with the specified value.

Fig 6: Identifying Fuel Quantity Graph

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

*) Minimum delivery rate cm³ /30 s

**) Voltage at the fuel pump with the engine off and the fuel pump running (approx. 2 Volts less than battery voltage).

Read-out example:

During test, a voltage of 12.5 Volts is measured at battery. Since voltage at the pump is approx. 2 Volts less than battery voltage, there is a minimum delivery rate of approx. 580 cm³ /30 s.

If the minimum delivery rate is not obtained:

-- Check fuel lines for restrictions (kinks) or clogging.

If no malfunction can be found:

-- Disconnect the supply hose -1- from the fuel filter input.

Fig 7: Identifying Pressure Tool To Check Fuel Pump Non-Return Valve

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Connect a High pressure fuel gauge between the fuel filter and fuel supply line.

-- Repeat the delivery rate test.

If the minimum delivery rate is obtained:

-- Replace the fuel filter. Refer to FUEL SYSTEM COMPONENTS .

If the minimum delivery rate is not obtained:

-- Remove the fuel pump and check the strainer filter for dirt.

If no malfunctions have been found:

-- Assembly is performed in the reverse of the removal.

Final procedures

After the repair work, the following work steps must be performed in the following sequence:

Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .