Fuel Pump, Checking

Fuel Pumps, Checking

Special tools and equipment
- Fluke 83 Multimeter
- VAG 1348/3A Remote control with VAG 1348/3-2 Adaptor cable
- VAG 1466 Fuel analyzer
- VAG 1527B LED tester
- VW 1594 Adaptor kit
- 3217 Collar nut wrench
- VAG 1318 Pressure tester
- VAG 1318/1 Hose
- 1318/10 Adaptor
- 1318/11 Adaptor
- Measuring container
- Wiring diagram

Checking conditions
- Battery voltage: 11.5 Volts minimum
- Fuse 18 OK







- Remove sealing plug -1- on fuel pressure regulator bracket.
- Connect VAG 1318 pressure gauge to test connection using VAG 1318/10 adapter and hose VAG 1318/1.
- Pressure gauge lever must be closed (-arrow- at right angle to direction of flow)


WARNING!
Fuel system is under pressure! Before opening system, place a rag around connection and release pressure by slowly loosening connection.


- Start engine and let idle.
- Check fuel pressure.
- Specification: approx. 2.5 bar

If fuel pressure does not build-up:
- Switch off ignition.
- Remove cover in front of fuse/relay panel.







- Remove fuel pump relay -J17- from fuse relay panel position 12.


NOTE:
- If tools are required to pull relays or control modules from relay panel, first disconnect battery ground.
- Obtain radio Anti-theft code before disconnecting battery ground strap.
- Connect remote control VAG 1348/3A between terminal 4 and battery positive (+) using adapter cable VAG 1348/3-2.
- Operate remote control.

If fuel pressure builds-up:
- Check activation of fuel pump relay.

If fuel pressure is not built-up.
- Remove driver's seat.
- Lift carpeting above parking brake lever.
- Remove access plate.







- Disconnect 4-pin connector from fuel tank flange.







- Connect VAG 1527B LED tester to connector outer terminals using jumper wires from VW 1594 adaptor kit.
- Operate remote control.
- LED tester must light up.

If LED does not light up:
- Locate and eliminate open circuit using wiring diagram.

If LED lights up (voltage supply OK):







- Unscrew collar nut using 3217 tool.
- Check for good wire connection between flange and fuel pump.

If no open circuit can be found:
- Replace malfunctioning fuel pump.

Delivery rate, checking
- Voltage supply OK
- VAG 1348/3A Remote control connected
- Remove filler cap from fuel tank filler neck.


WARNING!
Fuel system is under pressure! Before opening system, place a rag around connection and release pressure by slowly loosening connection.







- Disconnect fuel supply line -1- from fuel pipe.
- Connect the VAG 1318 pressure gauge to fuel supply line -1- using 1318/10 adapter.
- Push VAG 1318/1 hose on adapter VAG 1318/11 on pressure gauge and hold hose in measuring container.
- Open pressure gauge tap.
- Lever must point in direction of flow -A-.
- Operate VAG 1348/3A remote control and slowly close lever until pressure gauge shows 3 bar. Once you reached pressure, do not move lever any further.
- Empty measuring container.
- Measure battery voltage using Fluke 83 multimeter.
- Operate remote control for 30 seconds.







- Compare quantity of fuel delivered with specification.

*) Minimum delivery in cc's per 30 seconds
**) Voltage at fuel pump (running) with engine not running (approx. 2 volts less than battery voltage)

Example:
For this example, 12.2 volts was measured at battery. If voltage at pump is approx. 2 volts less than battery voltage, it equals a minimum delivery of 550 cc's in 30 seconds.

If minimum delivery rate is not obtained:
- Check fuel lines for possible restrictions, kinks or blockages.







- Disconnect supply line -1- from fuel filter inlet.
- Connect VAG 1318 pressure gauge to hose using 1318/10 adaptor.
- Repeat delivery rate check.

If minimum delivery rate was not reached:
- Replace fuel filter.

If minimum delivery rate was still not reached:
- Remove fuel delivery unit and inspect strainer for clogging.

If you did not find malfunctions to this point, fuel pump is inoperative.
- Replace fuel delivery unit.

If you measured minimum delivery but you still suspect an intermittent fuel supply system malfunction:
- Reconnect all disconnected fuel lines.
- Remove driver's seat.
- Lift carpet above parking brake lever.
- Remove cover plate.







- Connect Fluke 83 multimeter to red/yellow wire with Fluke current measuring adaptor.
- Start engine and let idle.
- Measure fuel pump amperage draw.
- Specification: 8 amps maximum


NOTE: If fuel system malfunction is intermittent, you can also perform check during a test drive with a 2nd technician to read data.


If amperage draw is too high, fuel pump is malfunctioning.
- Replace fuel delivery unit.

Fuel pump check valve, checking
- VAG 1348/3A Remote control connected
- VAG 1318 Pressure gauge connected to fuel supply line


NOTE: This setup checks entire fuel supply line from fuel delivery unit to VAG 1318 pressure gauge.







- Close pressure gauge tap position -B- (lever at right angle to direction of flow).
- Operate remote control at short intervals until a pressure of approx. 3 bar has built-up.
- If pressure builds up too high, lower excess pressure by carefully opening tap.


WARNING!
Danger of fuel spray when opening pressure tap. Hold open end of pressure gauge over a suitable container to catch over spray.


- Observe pressure drop.
- After 10 minutes pressure must not drop below 2.2 bar.
- Check line connections for leaks and/or replace fuel delivery unit if necessary.