Fuel Consumption Sender; Check; Removal, Adjust

Fuel Consumption Sender:

Fuel consumption sender, checking (air flow sensor potentiometer)
- disconnect plug from fuel consumption sender (air flow sensor potentiometer) (arrow 2)
- disconnect air intake elbow leading to oil cooler
- remove air filter from lower bracket
- remove air filter at top (arrow 1)

Test Lead (VW 1501):

- connect test lead (VW 1501) between fuel consumption sender (air flow sensor potentiometer) and plug connector
- connect voltmeter to VW 1501 between connectors 1 and 3
- switch ignition ON
- specified value:
^ 5.0 V

IF NO

- repair break in wiring using current flow diagram
- connect voltmeter to VW 1501 - between connectors 2 and 3
^ sensor plate in rest position specified value:
^ 0.0 V
IF NO, - replace fuel consumption sender (air flow sensor potentiometer)

If the specified value is attained:
- detach air intake elbow from air flow sensor

Adjusting Tool (VW 1348/1):

- attach adjusting tool (VW 1348/1)

Note

Before mounting tool set slide (2) at extreme upper position. Attach adjusting tool centrally on the rim of air flow sensor. Pointer (3) must face toward fuel distributor.

- push in slide (2) as far as it will go
- turn in adjuster screw (1) until magnetic tip contacts mounting screw of sensor plate (sensor plate in rest position)
- pull up slide (2) of adjusting tool to first stop (idle position)
- specified value:
^ 0.2-0.5 V
- pull up slide (2) of adjusting tool to second stop (full throttle position)
- specified value:
^ 4.0-4.5 V
If specified values are not attained, - replace fuel consumption sender (air flow sensor potentiometer)

If specified values attained
- check wiring between fuel consumption sender and computer as follows:
Work sequence

- remove instrument cluster

10 Point Connector for Computer:

3 Point Connector for Fuel Consumption Sender (Air Flow Sensor Potentiometer):

- check continuity (using ohmmeter between 10 point computer connector and 3 point fuel consumption sender) (air flow sensor potentiometer) in the following order:

10 point 3 point
connector connector
7 to 1
8 to 3
9 to 2

- Specified value:
^ approx. 0.2 ohm

If specified values are not obtained for all measurements, - repair wiring break using current flow diagram

Air Intake Elbow:

- remove air intake elbow

Mixture Control Unit:

- detach complete mixture control unit from air cleaner housing (arrows) (fuel line on fuel distributor remain connected)

Air Flow Sensor Potentiometer:

- disconnect plug from fuel consumption display sender (air flow sensor potentiometer) (arrow)

Note

Do not touch contact surface of sender or contact tabs in air flow sensor

Fuel Consumption Sender:

- remove screws holding fuel consumption sender (arrows) to air flow sensor, and pull sender out
- install new fuel consumption sender (air flow sensor potentiometer) and adjust

Note

Always replace all gaskets when installing new sender.

Test Lead (VW 1501):

Fuel consumption display sender (air flow sensor potentiometer), adjusting

Note

Adjust only after replacing sender.
- connect test lead (VW 1501) between fuel consumption sender (air flow sensor potentiometer) and connector

Mixture Control Unit:

- position mixture control unit so that sensor plate can move freely

Adjusting Tool VW 1348/1:

- fit adjusting tool VW 1348/1.
- set slide (2) at extreme upper position.
- fit appliance centrally on rim of air flow sensor.
- point (3) must point towards fuel distributor.
- push in slide (2) to stop

- tighten adjusting screw (1) until magnetic tip contacts mounting screw on sensor plate (sensor plate in rest position)
- connect voltmeter to VW 1501 between test leads 2 and 3
- switch ignition ON

First Stop:

- pull up slide (2) of adjusting tool to first stop (idle position)

Specified value:
^ 0.2-0.5 V

If NO, - unscrew retaining screws on fuel consumption sender (arrows)
- move sender in slots until correct reading is obtained
- tighten retaining screws

Second Stop:

If specified value was obtained, - perform full throttle test as follows:
- pull up slide (2) of adjusting tool to second stop (full throttle position)

Specified value:
^ 4.0-4.5 V

If NO, - repeat test in idle position or repeat basic adjustment of adjusting tool

If specified value was obtained:
- push slide (2) down as far as it will go

Specified value:
^ 0.0 V

If specified value is not obtained, - repeat test in idle and full throttle position

If specified values are still not obtained even after repeating adjustment, - replace air flow sensor

If specified values were obtained, - seal retaining screws with paint