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Home >> Volkswagen >> 1999 >> Passat Syncro Sedan (3B2) V6-2.8L (AHA) >> Repair and Diagnosis >> Powertrain Management >> Fuel Delivery and Air Induction >> Fuel Pump >> Testing and Inspection >> With Generic Scan Tool

With Generic Scan Tool



Fuel Pump (FP), checking

Recommended special tools and equipment









- 3087 Wrench
- 3217 Ring nut spanner
- V.A.G 1318 Pressure gauge
- V.A.G 1318/10 Adapter
- V.A.G 1318/11 Adapter
- V.A.G 1318/12 Adapter
- V.A.G 1332 Torque wrench (40 to 200 Nm)
- V.A.G 1348/3A Remote control connection with
- V.A.G 1348/3-2 adapter cable
- V.A.G 1466 Electrical circuit tester
- V.A.G 1527B Voltage tester
- V.A.G 1594A Connector test set
- V.A.G 1715 multimeter
- Measuring container
- Wiring diagram

All Wheel Drive (AWD) vehicles
- 3087 Wrench

Front Wheel Drive (FWD) vehicles
- 3217 Ring nut spanner

Test requirements






- The respective fuses of Fuel Pump (FP) -G6- must be OK:
- Battery voltage must be at least 11.5 volts.
- All electrical consumers like, for example, lights and rear window heating must be switched off.
- Parking brake must be engaged or else daylight driving lights will be switched on.

Checking function and voltage supply

All Wheel Drive (AWD) vehicles
- Remove rear seat bench.
- Remove floor cover.

Front Wheel Drive (FWD) vehicles
- Remove luggage compartment floor cover.

Continuation for all vehicles
- Operate starter briefly. Fuel Pump (FP) must audibly start up.
- Switch off ignition.

If Fuel Pump (FP) does not start up:
- Remove cover in front of fuse holder.







- Remove fuse 28 from fuse holder.
- Connect V.A.G 1348/3A remote control connection to Fuel Pump (FP) and B+ at terminal 28a using V.A.G 1348/3-2 adapter cable.
- Operate remote control.

If Fuel Pump (FP) runs:
- Check activation of Fuel Pump (FP) Relay -J17- according to wiring diagram:

If Fuel Pump (FP) does not run:







- Disconnect 4-pin harness connector from flange at fuel tank (arrow).







- Connect V.A.G 1527 voltage tester to the outer terminals of the connector.
- Operate remote control.
LED must light up.

LED does not light up:
- Locate and repair open circuit using wiring diagram:
LED lights up (voltage supply OK):







All Wheel Drive (AWD) vehicles
- Use 3087 wrench to remove locking ring.







Front Wheel Drive (FWD) vehicles
- Use 3217 ring nut spanner to remove union nut.

Continuation for all vehicles
- Check whether electrical wires between flange and Fuel Pump (FP) are connected.

If there are no open circuits:
- Fuel Pump (FP) malfunctioning, replace Fuel Pump (FP).

Checking fuel delivery

Test requirements
- Voltage supply OK
- V.A.G 1348/3A remote control connection

Test sequence
- Remove fuel filler cap from fuel filler neck.
- Remove intake manifold cover.







- Open threaded connection (arrow) and catch exiting fuel using a rag.

WARNING:
- The fuel or fuel lines in fuel system can become very hot (danger of scalding)!
- In addition, the fuel system is under pressure! Before opening the system, place rags around the connection area and release pressure by carefully loosening the connection!
- Wear protective goggles and protective gloves when working on the fuel system!







- Connect V.A.G 1318 pressure gauge to fuel supply line using V.A.G 1318/12 adapter.
- Connect a standard hose to V.A.G 1318/11 adapter of pressure gauge and hold into measuring container.
- Open shut-off valve of pressure gauge. Lever will point in direction of flow -A-.
- Operate remote control. Slowly close shut-off valve until pressure gauge displays

4 bar is indicated.

Do not change position of shut-off valve any more.

- Empty the measuring container.
- Delivery rate of Fuel Pump (FP) is dependent on battery voltage. Therefore, connect multimeter to vehicle battery using adapter cables.
- Operate remote control
30 seconds long and measure battery voltage.







- Compare fuel quantity pumped with specified value.

*) Minimum delivery rate cubic cm/30 s
**) Voltage at Fuel Pump (FP) with engine off and pump running (approx. 2 volts less than battery voltage).

Read-out example:
During test, a voltage of 12.2 volts is measured at battery. Since the voltage at the pump is approx. 2 volts less than battery voltage, there is a minimum delivery rate of 550 cubic cm/30 s.

If minimum delivery quantity is not obtained:
- Check fuel lines for possible restrictions (kinks) or clogging.







All Wheel Drive (AWD) vehicles
- Disconnect supply line -1- from fuel filter input.







Front Wheel Drive (FWD) vehicles
- Disconnect supply line -1- from fuel filter input.

Continuation for all vehicles
- Connect V.A.G 1318 pressure gauge to hose using V.A.G 1318/10 adapter.
- Repeat test of delivery quantity.

If minimum delivery quantity is now obtained:
- Replace fuel filter.

If minimum delivery quantity is still not obtained:
- Remove Fuel Pump (FP) and check filter strainer for dirt.

Only if no malfunctions have been found yet:
- Fuel Pump (FP) malfunctioning, replace Fuel Pump (FP)

Delivery rate has been obtained, but malfunctions are still suspected in the fuel supply (e.g. sporadic loss of fuel supply):

Check Fuel Pump (FP) current draw as follows:
- Reconnect all disconnected fuel lines.

All Wheel Drive (AWD) vehicles
- Remove rear seat bench.
- Remove floor cover.

Front Wheel Drive (FWD) vehicles
- Remove luggage compartment floor cover.







Continuation for all vehicles
- Connect V.A.G 1715 multimeter with current probe to green/yellow wire from wiring harness.
- Start engine and let run at idle.
- Measure Fuel Pump (FP) current draw.

Specified value: max: 8 amperes


NOTE:
If disturbance in fuel system is sporadic, test can also be performed during a road test, but a 2nd person is required.


If current draw is exceeded:
- Fuel Pump (FP) malfunctioning, replace Fuel Pump (FP)

Check Fuel Pump (FP) check-valve

Test requirements
- Remote control connected
- Pressure gauge connected to the fuel supply line of fuel supply tube

Test sequence


NOTE:
This test also checks the connections of the fuel supply line from Fuel Pump (FP) to connection point of pressure gauge for proper seal.







- Close pressure gauge shut-off valve (lever perpendicular to direction of flow, -position B-).
- Operate remote control in short intervals until a positive pressure of approx. 4 bar has built up.
- If excess pressure is built up, reduce pressure by carefully opening shut-off valve.

WARNING: Danger of spray when opening shut-off valve. Hold container in front of open connection on pressure gauge.

- Observe pressure drop on pressure gauge. Pressure must not fall below
Engine cold 2.2 bar
Engine hot 3.0 bar
within 10 minutes.

If pressure drops further:
- Check line connections for proper seal.

If no malfunctions are found in lines:
- Fuel Pump (FP) malfunctioning, replace Fuel Pump (FP)
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