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Fuel pump retaining valve - check > < Test conditions

Polo Mk4

Test sequence
Test sequence
  Note
Fuel pump intake flow is measured at 3 bar. Because of that fuel pressure must be checked before measuring intake flow.
–  Remove cover from fuel refilling nozzle.
   
–  Loosen return tube -1- from fuel pressure regulator.
  Note
To unlock fuel ducts, push safety ring inwards.
–  Connect Adapter set -V.A.G 1318/17- to fuel pressure regulator and hold a graded container on the other adapter end.
–  Start remote control -V.A.G 1348/3A- for approximately 5 seconds to fill fuel filter.
–  Drain graded container.
–  Fuel pump intake flow depends on voltage. Therefore, connect multimeter with Measuring appliance set -V.A.G 1594/C- auxiliary cables to two fuel pump external contacts (with connector fitted).
–  Activate remote control for 30 seconds and measure voltage.
  N20-0526
–  Compare fuel flow to theoretical value.
1)  Minimum flow cm3/30 s
2)  Fuel pump voltage when engine is stopped and pump is working (approximately 2 volts less than battery tension).
Reading examples:
During test a 10.5 voltage is measured. With pump at this voltage result shown is minimum flow of 540 cm3/30s.
If minimum flow is not reached:
–  Check if filter intake tube has bottlenecks (folds) or obstructions.
If fuel tubes are in order
–  Check fuel flow before fuel filter.
  WARNING
Fuel supply hose is under pressure! Before loosening hose junctions, place a cloth around them. Next, eliminate pressure removing hose carefully.
  N20-0134
–  Disconnect tubes -1- from fuel filter entrance.
  Note
To unlock fuel ducts, push safety ring inwards.
–  Connect pressure meter K-Jetronic test appliance -V.A.G 1318/- with Adapter set -V.A.G 1318/17- as shown.
–  Fasten adapter hose Adapter -V.A.G 1318/1- to Adapter -V.A.G 1318/11- of pressure meter and hold it inside a graded container.
–  Open pressure measuring blocking valve. Lever will point toward flow direction -A-.
–  Activate remote control -V.A.G 1348/3A-, slowly closing the valve until manometer shows 3 bar positive pressure. Do not change again position of blocking valve.
–  Drain graded container.
–  Activate again remote control for 30 seconds. Compare fuel flow with value noticed on first measuring.
If minimum fuel flow is reached:
–  Replace fuel filter.
If minimum fuel flow is not reached:
–  Remove fuel pump and check whether there is dirt in the filter.
if no irregularity is observed this far:
–  Replace fuel pump.
If desired fuel flow is reached but there is the possibility that -fuel supply has a fault (like fuel supply temporary fault):
–  Measure fuel pump current consumption as follows:
–  Connect again all fuel hoses.
  N20-0531
–  Connect o Multimeter -V.A.G 1715/- to green/yellow harness cable with current breaking clamp.
–  Start engine and keep-it in slow gear.
–  Measure fuel pump current consumption. Theoretical value: Maximum 8 amperes.
  Note
If it is a temporary fault in the fuel system, checking may also be done during test drive, and in that case the participation of a second person is necessary.
In case of excessive current consumption:
–  Damaged fuel pump, replace fuel pump
  N20-0402

Fuel pump retaining valve - check > < Test conditions