Checking fuel delivery rate of fuel pump, vehicles with 6.0 bar low pressure fuel system — VW

Checking fuel delivery rate of
fuel pump
, vehicles with 6.0 bar low pressure fuel system
Note
Applies for version A and version B.
Special tools and workshop equipment required
Hand-held multimeter
V.A.G 1526D
Test instrument adapter/DSO (5-pin)
VAS 5565
Vehicle diagnosis, testing and information system
VAS 5051B
Pressure gauge
VAS 6551
Hose adapter set
VAS 6551/5
Adapters
VAS 6551/5-1
Hose adapter
VAS 6551/5-2
Hose adapter
VAS 6551/5-3
Test prerequisites
Delivery pressure of fuel pump (fuel low pressure) was previously checked.
Fuel tank at least
3
/
4
full.
Connect charger or battery voltage above 12.5 volts.
Test sequence
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.
Lower fuel tank
Chapter
.
Pull off fuel supply line (black or black marking)
2
from fuel delivery unit
Chapter
“
Separating plug-in connectors
”
.
Collect escaping fuel with a cleaning cloth.
Connect connection
A
of
pressure tester
VAS 6551
with line
VAS 6551/1
to open end of fuel delivery unit.
Close shut-off valves
“B”
+
“C”
of
pressure tester
VAS 6551
.
From connection
B
, route
hose adapter
VAS 6551/2
into a ≤ 3-litre measuring container
3
and hold there.
Switch on
pressure tester
VAS 6551
by pressing
On/Off
button.
Switch ignition on.
Connect
vehicle diagnostic tester
, and carry out guided function
“Check electrical fuel pump(s)”
.
Note
The fuel pump is now activated for 30 seconds.
Carefully open shut-off valve
“B”
completely.
Slowly close shut-off tap
“B”
again.
At the same time read pressure on
pressure tester
VAS 6551
.
Set specification to 5 ± 0.2 bar by carefully closing.
Drain measuring container.
Repeat function
“Checking electronic fuel pump(s)”
.
The amount of fuel delivered by the
fuel pump
depends on the voltage at the fuel delivery unit.
Therefore, also connect
multimeter
V.A.G 1526
to outputs
1
and
5
of
test instrument/DSO adapter 5-pin
VAS 5565
.
Test prerequisites
At RT = room temperature or fuel temperature of T = (20 ± 5)°C
At a pressure of 5 ± 0.2 bar at flange output
During the checking process, voltages ranging from 11 to 15 volts must be evident at the fuel pump. Measured at the flange connector of the delivery unit.
Carry out guided function
“Checking electronic fuel pump(s)”
.
Compare the amount of fuel delivered with the read value from the table.
*) Delivered amount of fuel in ml/30 s
**) Voltage at fuel delivery unit (V) with engine not running and pump running
Example:
During the test, a voltage of 12 V, for example, is measured at the fuel delivery unit.
The delivered amount of fuel is therefore 1100 ml/30 s.
If the required amount of delivered fuel is achieved, or if more is measured:
Fuel pump
is OK.
If the amount of fuel to be delivered by the
fuel pump
is not achieved, the following faults have occurred:
Battery voltage below 12.5 V (connect charger).
Fuel delivery unit filter strainer soiled. Check filter strainer for soiling.
Voltages in the range from 11 to 15 volts were not reached during the testing process.
Checking voltage supply of
fuel pump
Chapter
.
Check current consumption of
fuel pump
Chapter
.