The fuel gauge sender is mounted in the fuel tank. Access is via a hatch in
the boot/trunk/load space floor.
It is recommended to disconnect the battery negative lead before working on
remove trim on floor panel and undo the access hatch.
unplug wiring from sender.
unplug fuel lines (use rags to mop any spillage)
unscrew large plastic ring.
lift out sender unit.
if you are going this far it may pay to cost and/or have ready a new unit to
put back in.
Ted and David,
Although it may be a shot in the dark, I once had a conversation about
wiring with a tech who works at a nameless VW dealer - he said that there
were a number of Passats (?) that were brought in with problems with the
fuel gauge - when the top of the sender was accessed, there was COOLANT on
the top of the sender! Turns out, a leak in the coolant level sensor,
combined with well-sealed connectors, provided a rubber-encased conduit for
the pressurized coolant escaping the reservoir - right through the dash and
a number of harnesses. As you can imagine, the whole harness has to be
replaced (done under warranty in the case of the VW's).
You can check the output of the tank sender using a multimeter - resistance
value should correspond with a tank level (in the Bentley) - if it is a
flaky sender then you might see the resistance drop off if the car is
rocked. Although I am unfamiliar with the inside of an A4 tank, with a
5ktq, it is important to make sure that the sender float arm goes back in
exactly as it came out, otherwise it will hang up on the wires and fuel line
coming from the in-tank fuel pump.
1987 Audi 5kTQ - after numerous attempts, the gas gauge still stops at 1/4
1980 Audi 5k
1962 and '64 Auto Union DKW Junior deLuxes
(SPAM Blocker NOTE: Remove SHOES to reply)
Just a few notes to add to your excellent procedure description:
There's a release tab you'll have to depress to get the sender out.
You pretty much have to do it by feel since you can't see anything
once you stick your hand/arm into the tank. It might pay to pick up
a manual or try to find a picture of the setup before attempting
replacement. You might check on AudiWorld (www.audiworld.com) for
help with this.
Oh, and more thing ... do this on a nearly empty tank unless you enjoy
soaking your arm in gasoline.
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