Bleeding fuel line to metering pump V54 (filling with fuel) — VW

Bleeding fuel line to
metering pump
V54
(filling with fuel)
Note
Air or fuel vapour in the fuel supply to the auxiliary heater can lead to malfunction when the auxiliary heater is in combustion mode. To prevent air or fuel vapour from being drawn in by the
metering pump
V54
and conveyed to the auxiliary heater when the auxiliary heater is first switched on after performing repairs on the fuel tank or the fuel delivery unit, the fuel take-off pipe must be filled with fuel (bled) after performing repairs in this area.
The fuel line must be bled, for example, if the fuel line was removed and the entire fuel line is filled with air. If, for example, only the fuel delivery unit was removed and there is only a small amount of air in the fuel line; it is sufficient to switch on the auxiliary heater and let it run for some time (at least 10 minutes) in full load mode to check its operation after completing work on the fuel system.
After completing work on the fuel system, switch on the auxiliary heater, and let it run for some time (at least 10 minutes) in full load mode.
On vehicles with high-voltage system, it may not be possible to switch on the auxiliary heater via the control panel, depending on the charge level of the
hybrid battery unit
AX1
and the ambient temperature. If the
J255
gets the information that the
hybrid battery unit
AX1
is sufficiently charged, that there is sufficient power available to operate the
high-voltage heater (PTC)
Z115
and that the ambient temperature is above -10°C, the
J255
activates the
Z115
(the auxiliary heater is not activated). In this case, the auxiliary heater can be switched on using e.g. the
“Basic setting”
function. For additional information refer to
Vehicle diagnostic tester
in
“Guided fault finding”
mode.
Note
On vehicles with high-voltage system, the
metering pump
V54
1
cannot be accessed if the fuel tank is installed. Therefore, bleed fuel line
2
(and corresponding riser tube) leading to
metering pump
V54
after completing work on the fuel system of the auxiliary heater (e.g. following repair work on the fuel delivery unit or the
V54
1
).
Disconnect fuel line
4
leading from
V54
1
to auxiliary heater at connection
5
Rep. gr.
20
Plug-in connectors
(Separating plug-in connectors).
Note
Observe safety precautions when working on the fuel supply system
Rep. gr.
20
Safety instructions; Safety precautions when working on fuel supply system
.
Hold a container under the opened connection (e.g. the container of the
diesel extractor
VAS 5226
).
Activate
V54
1
e.g. via the function
“Line filling”
in
“Basic setting”
for the auxiliary heater for approx. 30 seconds;
Vehicle diagnostic tester
in
“Guided fault finding”
mode.
Observe the fuel which escapes at connection
5
.
Note
If after 30 seconds fuel escapes continuously from connection
5
, the fuel line is filled completely with fuel.
Connect fuel line to connection
5
.
After all removed components have been reinstalled, switch on the auxiliary heater, and let it run in full load mode for approx. 10 minutes.
Note
On vehicles with high-voltage system, it may not be possible to switch on the auxiliary heater via the control panel, depending on the charge level of the
hybrid battery unit
AX1
and the ambient temperature. If the
J255
gets the information that the
hybrid battery unit
AX1
is sufficiently charged, that there is sufficient power available to operate the
high-voltage heater (PTC)
Z115
and that the ambient temperature is above -10°C, the
J255
activates the
Z115
(the auxiliary heater is not activated). In this case, the auxiliary heater can be switched on using e.g. the
“Basic setting”
function. For additional information refer to
Vehicle diagnostic tester
in
“Guided fault finding”
mode.