Checking fuel delivery — AUDI

Test requirements:

Coolant temperature less than 50 oC (check at coolant temperature gauge in dash panel insert)
Ambient temperature less than 20 oC
Voltage of second battery at least 11 V

Sufficient fuel in tank (fuel gauge in dash panel insert must not be in red zone).

Switch off ignition.
Remove noise insulation.

=> General body repairs; Repair group 50; Front body; Removing and installing noise insulation
General body repairs
Front body
Removing and installing noise insulation

Disconnect fuel line -A- at auxiliary heater.
Hold fuel line into measuring vessel -B-.
Switch on auxiliary heater.

Switch off auxiliary heater as soon as fuel flows out of fuel line into measuring vessel and wait until fuel has stopped flowing.
Empty measuring vessel and once again hold fuel line into vessel.
Switch on auxiliary heater (Start of measurement).

Notes:

If ambient temperature is more than 20 oC, this can result in an incorrect measurement because of fuel evaporation.
Bubbles of vapour should not be present.
If metering pump does not start pumping 30 seconds after switching on auxiliary heater:

=> Binder "Fault finding heater, air conditioner"

Measure voltage of second battery.
Measure fuel delivery of metering pump after completion of repeat start (green indicator light in preselector/timer is no longer illuminated about 5 minutes after switching on auxiliary heater).

Compare quantity delivered with specified quantity in diagram:

Vehicles with petrol engine

A -
Battery voltage
B -
Delivery in cm3(millilitres)
C -
Tolerance range for specified delivery

Vehicles with diesel engine

A -
Battery voltage
B -
Delivery in cm3(millilitres)
C -
Tolerance range for specified delivery

Note:

A smaller quantity of diesel fuel is adequate for operating auxiliary heater as a result of the higher heating value.

If the fuel delivery rate is outside the tolerance range:

Measure delivery directly at metering pump.
Check that fuel line is not blocked.
Check wiring between auxiliary heater control unit -J162 and metering pump -V54:

=> "Current flow diagrams, Electrical fault finding and fitting locations" binder

Check wiring to auxiliary heater control unit -J162:

=> "Current flow diagrams, Electrical fault finding and fitting locations" binder

Note:

Contact 6 in connector -D- must not be assigned except on models with diesel engine.

If auxiliary heater does not start easily at low ambient temperatures (heater does not start until after repeat start) and if quantity of fuel pumped is in lower range of diagram:

Test CO2-concentration in exhaust => Page
82-43
.
Test fuel delivery of fuel line and wiring, as described above.
If no fault is found, replace metering pump.
Observe notes on Page
82-24
for vehicles with diesel engine.