Checking fuel system pressurisation pump G6 - TFSI vehicles — AUDI

Checking
fuel system pressurisation pump
G6
- TFSI vehicles
Special tools and workshop equipment required
Pressure tester
VAS 6550
with
hoses
VAS 6550/2
Adapter set
VAS 6550/3
Pressure control valve
VAS 6550/4
Vehicle diagnostic tester
Fuel-resistant measuring container
A - Checking fuel delivery rate
Observe test conditions
Chapter
.
Open tank flap.
Remove filler cap
arrow
for fuel filler neck.
Remove engine cover panel
Engine
Rep. gr.
10
Engine cover panel; Removing and installing engine cover panel
.
1.4 ltr. TFSI vehicles:
WARNING
Risk of injury - fuel system operates under high pressure.
To reduce the pressure in the fuel system, wrap a clean cloth around the connection and carefully loosen the connection.
Disconnect fuel hose
1
. Disconnecting plug-in connectors
Chapter
Note
Disregard
item 2
.
Connect
pressure tester
VAS 6550
to fuel supply line with
hose
VAS 6550/2
.
Attach
pressure control valve
VAS 6550/4
and hold end of hose into fuel-resistant measuring container.
1.8 ltr./2.0 ltr. TFSI vehicles:
WARNING
The fuel system is pressurised.
Risk of injury as fuel may spray out.
Wear safety goggles.
Wear protective gloves.
Release pressure (wrap clean cloth around connection and open connection carefully).
Disconnect fuel hose
1
. Disconnecting plug-in connectors
Chapter
Note
Disregard
item 2
.
Connect
pressure tester
VAS 6550
to fuel supply hose using
hose
VAS 6550/2
.
Attach
pressure control valve
VAS 6550/4
and hold end of hose into fuel-resistant measuring container.
All vehicles (continued):
Switch on
pressure tester
VAS 6550
item 1
by pressing
On/Off
button.
Note
To measure the fuel delivery rate, pressure must first be built up in the fuel line; the fuel pump must then operate against this pressure during the measurement. This pressure can be built up using the
pressure control valve
VAS 6550/4
as follows:
Open cut-off valves
A and B
.
Levers must point in direction of flow.
Caution
Risk of fuel escaping.
Cut-off valve
C
must be closed.
The lever should point perpendicular to direction of flow.
Connect
vehicle diagnostic tester
.
Switch on ignition.
Select and start
Self-diagnosis
mode.
Power train
Engine
01 - Self-diagnosis compatible systems
01 - Engine electronics
Basic setting
Empty fuel tank
Start basic setting without measured values: The fuel pump will start running.
Build up pressure in fuel system by turning adjuster screw
1
on
pressure control valve
VAS 6550/4
until correct pressure is reached.
Specification: 4.5 bar
From this point on, do not turn adjuster screw
1
.
Press
Stop
.
Drain measuring container.
For measurement, press
Start
again and let fuel pump run for 15 seconds.
Press
Stop
after 15 seconds.
Check amount of fuel delivered in measuring container.
Specification: minimum delivery rate 400 cm
3
/15 sec.
If the minimum delivery rate is attained:
Fuel delivery unit with fuel filter, fuel pressure regulator and fuel supply line OK.
If minimum delivery rate is not achieved, check for the following causes:
Fuel delivery unit with integrated fuel filter defective.
Fuel pressure regulator in fuel delivery unit defective.
Fuel supply line crushed.
Note
To find the precise cause of the fault, a pressure test must be performed on the fuel supply line as described below.
B - Pressure test on fuel supply line
Leave measuring equipment connected in the same way as for measuring the fuel delivery rate.
Vehicle diagnostic tester
still connected.
Switch on
pressure tester
VAS 6550
item 1
by pressing
On/Off
button.
Open cut-off valves
A and B
.
Levers must point in direction of flow.
Caution
Risk of fuel escaping.
Cut-off valve
C
must be closed.
The lever should point perpendicular to direction of flow.
Press
Start
on
vehicle diagnostic tester
display to start the fuel pump.
When fuel emerging is free of bubbles, close cut-off valve
B
to allow fuel pressure to build up.
The lever should point perpendicular to direction of flow.
Read fuel pressure off
pressure tester
VAS 6550
:
Specification: 6.0 ... 8.0 bar
Press
Stop
.
If specification is attained although fuel delivery rate was not OK:
Fuel filter in fuel delivery unit blocked or fuel supply line crushed.
If specification is not attained:
Fuel delivery unit or fuel pressure regulator in fuel tank defective.
C - Checking residual pressure
Check system for leaks and check residual pressure by watching drop in pressure on
pressure tester
VAS 6550
:
After 10 minutes pressure should still be at least 3 bar.
If the residual pressure drops below 3 bar:
Check fuel lines and their connections for leaks.
Non-return valve in fuel pump is leaking, renew fuel delivery unit
Chapter
.
Assembling
Installation is carried out in the reverse order; note the following:
The ignition must be switched off.
Note
Before removing the pressure tester
1
, release the fuel pressure by opening the cut-off valves
B, C
and allowing fuel to drain off into a measuring container.
Detach
pressure tester
VAS 6550
together with connection leads.
Connect fuel supply line, making sure it engages audibly.
Press fuel supply line in again and then pull to check that plug-in connector is correctly engaged.