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Removing and installing the fuel pressure regulating valveN276 > < Check the fuel system for tightness

Fabia Mk2

Check fuel pressure regulating valveN276
Check fuel pressure regulating valve -N276-
   
The fuel pressure regulating valve -N276--5- is located in the fuel distributor.
On this engine, the fuel pressure regulating valve -N276- has 2 functions:
t  At cold start, it opens at a certain low temperature. The warmed fuel from the fuel distributor is then led back into the feed line in front of the fuel filter. This prevents the fuel filter from clogging at low temperatures.
t  During vehicle over-run conditions, it regulates the fuel pressure in the fuel distributor.
Special tools and workshop equipment required
t  Suitable auxiliary hose for connection to the fuel return-flow line.
t  Fuel tank, approx. 200 ml.
Test condition
l  If necessary, allow engine to run until fuel temperature is at least 20 °C and the fuel is warm.
Determine fuel temperature:
–  Connect vehicle diagnosis, measurement and information system -VAS 505x-.
–  Select the correct vehicle in the „Targeted fault finding“.
–  Press button „Skip“.
–  Press „Selected Functions/Components“.
–  Select „Drive“.
–  Select „Engine CFWA (Rep. Gr. 01; 10-28)“.
–  Select „23 - fuel formation, injection“.
–  Select „Electrical Components“.
–  Select fuel temperature sender -G81-.
The fuel temperature is displayed.
Work procedure
  Caution
The test sequence must be absolutely observed.
l  Fuel temperature at least 20 °C.
l  The engine must only be idling. Otherwise the fuel pressure regulating valve -N276- can open and in turn the test will be inaccurate.
Observe safety measures and rules of cleanliness when undertaking all work on the fuel system → Chapter.
Observe the instructions for the fuel hose in the engine compartment → Chapter.
–  Remove engine cover → Chapter.
  Note
Collect the fuel which flows out with a cloth.
  N23-10390
–  Detach the hose -1- from the fuel return-flow line -2- → Chapter.
–  Close off the open hose end -arrow- with a suitable screw plug.
l  The hose connection must withstand a pressure of at least 1 MPa (10 bar).
–  Connect to the fuel return-flow line -2- using an auxiliary hose and put its end into a suitable catch pan for fuel.
–  Start engine and run for at least 3 minutes at idling speed.
l  In idle, no fuel must flow out of the fuel return-flow line -2-.
In the event that fuel flows out of the fuel return-flow line with the engine at idle, immediately switch off the engine.
  WARNING
Danger of liquid spraying out from the auxiliary hose of the fuel return-flow line after switching off the engine!
  Note
After switching off the engine, the fuel pressure regulating valve -N276- opens and the high pressure in the fuel distributor is removed via the fuel return-flow line through which the fuel flows out. This fuel must be collected.
–  Switch off engine.
If fuel has flown out of the fuel return-flow line when the engine was idling, the fuel pressure regulating valve -N276- is defective:
–  Replace fuel pressure regulating valve -N276- → Chapter.
  Note
Replace fuel hose to fuel return-flow line → Chapter.
–  Check fuel system for tightness → Chapter.
  S23-0253

Removing and installing the fuel pressure regulating valveN276 > < Check the fuel system for tightness