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Draining fuel filter > < Removing and installing injection pump

A4 Mk1

Bleeding fuel system
Bleeding fuel system
Special tools and workshop equipment required
t  Hose clamps for hoses up to 25 mm  -3094-
t  Remote control -V.A.G 1348/3A- with adapter cable -V.A.G 1348/3-2-
t  Hand-operated vacuum pump -V.A.G 1390- with bleeder container -V.A.G 1390/1-.
  WARNING
When bleeding the fuel system, make sure the inner section of the baffle housing (capacity approx. 0.5 litres) is permanently filled with fuel.
When the engine is not running (electric fuel pump off), the inner section of the baffle housing will only stay full if the tank is more than 2/3 full. For this reason, put in enough fuel to bring up the contents of the tank to more than 2/3 before bleeding the fuel system.
–  If necessary, put in fuel until tank contains approx. 50 litres. If you wish to avoid filling the fuel tank, observe the following note.
  Note
If you do not want to put more fuel in the tank because of tests that will be required later, the following method can be used to keep the baffle housing full of fuel while bleeding the system.
–  Open fuse box lid on left-hand side of dash panel.
–  Pull out fuse No. 28 from fuse holder.
   
–  Connect remote control -V.A.G 1348/3A- with adapter cable -V.A.G 1348/3-2- to right-hand terminal of fuse socket No. 28 -arrow-.
–  Connect crocodile clamp to vehicle battery (positive).
–  Keep remote control switch pressed while bleeding fuel system; fuel pump should run audibly.
  A20-0098
–  Using hose clamp up to 25 mm -3094-, clamp off fuel return line between filter and fuel tank.
  A20-0324
–  Disconnect return hose for injectors of right cylinder bank at injection pump.
–  Connect a short length of hose -3- to the free hose connection on the injection pump.
–  Insert a suitable adapter -2- from -V.A.G 1390/1- into the short length of hose.
–  Connect hose -1- between adapter and bleeder container -V.A.G 1390/1-.
–  Operate hand-operated vacuum pump and fill bleeder container -V.A.G 1390/1- three times in this way.
  WARNING
Empty the bleeder container before it becomes full. No fluid must be allowed to enter the hand-operated vacuum pump.
  Note
Air bubbles may still be visible in the hose even after the bleeder container has been filled 3 times.
–  Re-connect return hose to injection pump.
  A20-0325
–  Remove hose clamp up to Ø 25 mm -3094- from return line.
–  Put back fuse No. 28 if it has been removed.
–  Start engine and check fuel system for leaks (visual check).
  WARNING
Do not prolong attempted starting for more than 15 seconds.
If engine does not start, repeat bleed operation.
  A20-0324

Draining fuel filter > < Removing and installing injection pump