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Checking holding pressure > < Checking function and voltage supply

Polo Mk5

Checking fuel pressure
Checking fuel pressure
  Note
The fuel pressure regulator is located in the fuel filter.
Test procedure
  WARNING
The fuel line is under pressure.
Risk of injury to eyes and skin from fuel.
Wear eye protection and protective clothing to avoid eye injuries and skin contact. Before loosening hose connections, wrap a cloth around the connection. Then release pressure by carefully opening the connection point.
   
–  Separate fuel supply pipe coupling -1- and catch escaping fuel with a cleaning cloth.
  Note
Press in securing ring to release fuel line.
  N10-10528
–  Connect pressure tester -VAS 6550- to fuel supply line with adapter -VAS 6550/1- and -VAS 6550/2-.
–  Make sure that drain tap is closed and cut-off taps are open.
–  Start engine and run at idling speed.
–  Measure fuel pressure.
Specification: 3.90…4.20 bar
If fuel pressure is OK, check holding pressure → Chapter.
If the specification is exceeded:
–  Check return pipe between fuel filter and fuel pump for kinks and blockages.
If no fault is found:
–  Pressure limiting valve in fuel filter is defective. Renew fuel filter.
If the specification is not attained:
–  Check fuel pressure upstream of fuel filter. Proceed as follows to do this:
  N20-10628
–  Pull fuel supply line -arrow- off fuel filter.
  N20-10629
–  Connect pressure tester -VAS 6550- between fuel filter and fuel supply line with adapter -VAS 6550/1- and -VAS 6550/2-.
–  Make sure that drain tap is closed and cut-off taps are open.
–  Start engine and run at idling speed.
  N20-10630
–  Close shut-off tap -A- slowly. Pressure must rise to min. 6.0 bar. When 6.0 bar is reached, open shut-off tap again immediately.
If pressure has risen:
–  Fuel pump OK. Pressure limiting valve in fuel filter is defective. Renew fuel filter → Chapter.
If pressure does not rise:
–  Fuel pump is defective, renew fuel delivery unit → Chapter.
  N20-10598

Checking holding pressure > < Checking function and voltage supply