Fuel Level Indicator - Reads Incorrect

GROUP: 90

NUMBER: 93-01

DATE: April 3O, 1993

SUBJECT:
Incorrect Fuel Level indication

MODEL(s):
Passat 1990-1992 m.y.

Supersedes Technical Bulletin 90-92-04, April 30, 1992

Condition

Approx. 5 gallons (19 liters) of fuel are still in the tank when the fuel gauge needle indicates reserve due to one or more of the following conditions:

^ Incorrect calibration of fuel gauge
^ Fuel tank bottom is uneven
^ Fuel tank is bowed in because of kinked vent hose between fuel tank and filler pipe

Production

^ Calibration of fuel gauge revised as of production date 8/91
^ Introduction of adjustable fuel level sensor from vendor VDO as of 1/92, VIN: 31 N E 217279
^ Manufacturing process of fuel tank revised as of production date 7/91
^ Vent hose positioning on filler pipe changed as of 3/92, VIN 31 E 293 000

Service

- check fuel gauge according to Repair Manual, Repair Group 90.
- replace fuel gauge if not within specified values. The Parts Dept. will only supply improved fuel gauges.

Note
If the fuel gauge tests faulty and is replaced, no further action is required.

If the fuel gauge checks within the specified limits, then proceed with the following procedure:

- check if fuel tank is permanently deformed or bowed in, replace if fuel tank capacity has diminished by 1 gallon (3.8 liters) or more.

Note
Fuel tank replacement is normally not necessary. Only replace fuel tank in cases where tank is severely and permanently deformed or bowed in.

- check/adjust fuel level sensor as outlined below.

Warning!
Fire hazard. Do not smoke or have anything in the area that can ignite fuel or fumes.

- empty fuel tank using gas storage cart Tempo FM 3000 or equivalent.
- fill fuel tank with exactly 10 liters (2.65 gal.) of fuel.
- set multimeter Fluke 83 (US 1119) to Ohm measuring range.
- remove 4-pin fuel tank connector.
- connect multimeter test leads to terminals 1 and 2 (for fuel level sensor) of 4-pin connector on fuel tank, see wiring diagram.

^ resistance must be 180 +/- 5 Ohms

^ If NO,

Vehicles up to VIN 31 E 217 279, without adjustable fuel level sensor:

- remove fuel level sensor from the tank.
- bend fuel level sensor float arm up slight!y
- install fuel level sensor into tank.
- repeat resistance check.

^ resistance must be 180 +/- 5 Ohms

- repeat previous four steps as necessary until specified value is obtained.

Note
The fuel level sensor float must float in fuel during The resistance check.

- check vent hose for kinks, replace if necessary.

Vehicles from VIN 31 E 217279, with adjustable fuel level sensor:

- remove securing nut at adjustment screw using 6 mm socket.
- set multimeter Fluke 83 (US 1119) to Ohm measuring range
- remove 4-pin fuel tank connector
- connect multimeter test leads to terminals 1 and 2 (for fuel level sensor) of 4-pin connector on fuel tank.
- turn adjustment screw until multimeter reads 180 Ohm.
- after adjustment reinstall 6 mm nut and secure adjustment screw.
- verify that adjustment has not changed.
- check vent hose for kinks, replace if necessary.