Skoda Workshop Service and Repair Manuals > Fabia Mk1 > Drive unit | 1.0/37; 1.4/44; 1.4/50 kW MPI engine | Fuel supply, gas operation | Testing parts of fuel supply system | Inspecting the operating and holding pressure of the fuel | Inspecting the holding pressure of the fuel (checking the non-return valve of the fuel pump)

Inspecting the holding pressure of the fuel (checking the non-return valve of the fuel pump)

Note

t	The function of the non-return valve for the fuel pump is determined by inspecting the holding pressure of the fuel in the fuel system.

t	This test simultaneously checks the leaktightness of the fuel feed line from the fuel delivery unit through to the connecting point of the pressure gauge -V.A.G 1318-.

–	Connect the pressure gauge -V.A.G 1318- with the adapter -V.A.G 1318/23- and -A.G 1318/17- to the fuel feed line.

–	Close the shut-off cock of the pressure measuring device.

The lever then points in the position -B-.

–	Switch the ignition on and off so often until the fuel pressure on the pressure gauge does no longer rise.

–	Read off fuel pressure on the pressure gauge.

Specified value: at least 0.32 MPa (3.2 bar).

WARNING

Danger of liquid spraying out when opening the shut-off cock; hold the container in front of the free connection to the pressure gauge.

–	Lower the pressure to 0.3 MPa (3 bar) by carefully opening the shutoff cock.

–	Observe pressure drop at pressure gauge.

The pressure must not drop below 0.25 MPa (2.5 bar) after 10 minutes.

If the pressure still drops:

–	Check line connections for leaktightness.

If the wires are not found to be faulty, the non-return valve of the fuel pump is defective:

–	Replace fuel delivery unit → Chapter.