Checking fuel low-pressure ahead of fuel filter — VW

Checking fuel low-pressure ahead of fuel filter
Note
The adapter lines/leads 1 to 4 listed below are not required for the test.
Hose
VAS 6551/1
Hose
VAS 6551/2
Test lead
VAS 6551/3
Test lead
VAS 6551/4
Note
To perform test, use
Vehicle diagnostic tester
in conjunction with
test instrument box
VAS 6356
.
Special tools and workshop equipment required
Pressure tester
VAS 6551
Adapter set
VAS 6551/5
Vehicle diagnostic tester
Laptop, vehicle diagnosis (remote head)
VAS 6150 A
Instrument box
VAS 6356
Test prerequisites
Fuses must be OK.
Battery voltage at least 12 V
Ignition switched off
There must be at least 10 l of fuel in the fuel tank.
All electrical consumers, e.g. lights and rear window heating, must be switched off.
The fuel lines must not be kinked or damaged.
WARNING
Fuel supply lines are under pressure! 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 pulling hose off connection.
Procedure
WARNING
Read rules for cleanliness and the instructions for working on the fuel system
Chapter
.
Always follow these rules for cleanliness and instructions before starting work and while working on the fuel system.
Wrap a clean cloth around the connection before opening the fuel system, then carefully loosen the connection to release the pressure.
Separate quick-release coupling of
“black”
fuel supply line
3
from fuel filter
1
.
Note
To do this, press locking mechanism on quick-release coupling.
Collect escaping fuel with a cleaning cloth.
Connect hose
»-3«
from
adapter set
VAS 6551/5
to open fuel line (from fuel tank) and connection
A
of
pressure tester
VAS 6551
.
Open shut-off tap
A
of
pressure tester
VAS 6551
.
Connect hose
»-4«
from
adapter set
VAS 6551/5
to open connection on fuel filter and connection
B
of
pressure tester
VAS 6551
.
Open shut-off tap
B
of
pressure tester
VAS 6551
.
Close shut-off tap
C
of
pressure tester
VAS 6551
.
Switch on
pressure tester
VAS 6551
by pressing
on/off
pushbutton.
Connect
Vehicle diagnostic tester
or
laptop, vehicle diagnosis (remote head)
VAS 6150 A
to
test instrument box
VAS 6356
Activate fuel pump using guided function
“Fuel pump activation”
.
The fuel pump is activated.
Specification: ≥ 3.5 bar.
Note
If the specification has been reached and the fuel low-pressure on the high-pressure pump has not been checked yet, the fuel low-pressure downstream of fuel filter must be checked.
If the fuel low-pressure on the high-pressure pump has already been checked and the specification has not been reached, renew fuel filter
Chapter
.
Connect fuel supply line
3
to connection on fuel filter
1
.
Separate quick-release coupling of fuel supply line
2
from fuel filter
1
.
Note
To do this, press locking mechanism on quick-release coupling.
Collect escaping fuel with a cleaning cloth.
Connect hose
»-4«
from
adapter set
VAS 6551/5
to open connection on fuel filter and connection
A
of
pressure tester
VAS 6551
.
Open shut-off tap
A
of
pressure tester
VAS 6551
.
Connect hose
»-3«
from
adapter set
VAS 6551/5
to open fuel supply line leading to high-pressure pump
B
of
pressure tester
VAS 6551
.
Open shut-off tap
B
of
pressure tester
VAS 6551
.
Close shut-off tap
C
of
pressure tester
VAS 6551
.
Switch on
pressure tester
VAS 6551
by pressing
on/off
pushbutton.
Carefully open shut-off tap
B
.
Connect
Vehicle diagnostic tester
or
laptop, vehicle diagnosis (remote head)
VAS 6150 A
to
test instrument box
VAS 6356
Activate fuel pump using guided function
“Fuel pump activation”
.
The fuel pump is activated.
Specification: ≥ 3.5 bar.
If the specification is not attained:
Renewing fuel filter
Chapter