Testing system pressure, fuel pressure regulator and holding pressure — AUDI

ADW
Note:

The fuel pressure regulator regulates the fuel pressure according to the intake manifold pressure at the throttle valve unit.

Special tools, testers and auxiliary equipment required

Pressure tester V.A.G 1318
Adapter 1318/7
Adapter V.A.G 1318/13

Test requirements:

Fuel pump relay OK; checking =>Page
24-30
.
Fuel pump OK; checking:

=> 4-cyl. Injection engine (2-valve), Mechanical components; Repair Group 20; Removing and installing parts of fuel supply system, Testing fuel pump
4-cyl. Injection engine (2-valve), Mechanical components
Removing and installing parts of fuel supply system, Testing fuel pump

Battery voltage at least 11 V

Warning
Fuel system is pressurised. Before opening the system place a cloth around the connection. Then release pressure by carefully loosening the connection.
Slacken the bolted connection -arrow- of the fuel supply pipe.
Connect pressure measuring device V.A.G 1318 to the fuel supply pipe using adapters V.A.G 1318/7 and V.A.G 1318/13.

Note:

The shut-off cock of the pressure measuring device should be open (lever facing in the direction of flow).

Start engine and run at idling speed.
Measure the fuel pressure.
Specification: approx. 2,5 bars

Note:

If no fuel pressure is built up, check that the fuel feed and fuel return-flow lines have not been interchanged.

Pull vacuum hose off fuel pressure regulator.
The fuel pressure should rise to approx. 3.0 bar.

Switch off ignition.
Test for leaks and holding pressure by watching pressure drop on gauge.
After 10 minutes the remaining pressure should be at least 2 bar.

If the holding pressure drops below 2 bars:

Start engine and run at idling speed.
After the pressure has built-up switch off ignition and at the same time clamp-off the return pipe on fuel manifold.
Watch pressure drop on gauge.

If the pressure does not drop:

Replace fuel pressure regulator

If the pressure drops again:

Test pipe connections, O rings on fuel manifold and injectors for leaks.
Test the cold start valve => Page
24-49
Test pressure gauge for leaks
Test fuel pump non-return valve.

=> 4-cyl. Injection engine (2-valve), Mechanical components; Repair Group 20; Removing and installing parts of fuel supply system, Testing fuel pump
4-cyl. Injection engine (2-valve), Mechanical components
Removing and installing parts of fuel supply system, Testing fuel pump

Note:

Before removing the pressure gauge, release fuel pressure at the gauge.