Tandem Pump, Checking

Tandem Pump, Checking

Special tools, testers and auxiliary items required







- Pressure gauge VAS 5187







- Torque wrench (5 to 50 Nm) V.A.G 1331
- Vehicle diagnostic, testing, and information system VAS 5051
- Diagnostic cable VAS 5051/6A

Conditions
- Coolant temperature must be at least 85 degrees C.
- Pump-Injector units O.K.
- Fuel filter and fuel lines must not be plugged.
- Fuel level sensor must be OK.

Work sequence
- Loosen charge air tube and set aside.







- Remove locking bolt - arrow -.







- Install pressure gauge VAS 5187 as shown.
- Secure charge air tube in place again.
- Start engine and run at idle speed.
- Connect vehicle diagnostic, testing, and information system VAS 5051 and select operating mode "Vehicle self-diagnosis".
- Press button "01 - Engine electronics" on display.
- Press diagnostic function"08 - Read measured value block".
- Using number keypad, enter display group "1" and acknowledge entry with Q-key.
- Read idle RPM in display field "1".
- Increase engine speed to 4000 RPM.
- Observe displayed pressure on pressure gauge.
Specification: min. 7.5 bar
- Return engine to idle speed.

If the specification is not obtained:
- Clamp return line closed between fuel filter and tandem pump with a hose clamp.
- Increase engine speed to 4000 RPM.
- Observe displayed pressure on pressure gauge.
Specification: min. 7.5 bar
- Return engine to idle speed.

If the specification is now obtained:
- Pressure loss at Pump-Injector unit.
- Replace O-rings of Pump-Injector unit.

If the specification is not obtained:
- Replace tandem pump Tandem pump, removing and installing.

NOTE: After removing the pressure gauge, fasten the locking bolt to 25 Nm. Always replace the seal.