From: Dan [dbrindle@kondratyev.com]
Sent: Saturday, October 28, 2000 12:52 AM
To: 928
Subject: [928] RE: lousy gas gauge for '82 shark

Here is a procedure to test the fuel gauge system.  I assume no one replied
since you did not do the normal check out to help isolate the problem.
(Although I thought I sent some e-mail to someone about trouble shooting the
tank unit)  Unless it is a known gremlin that has a magic fix then you
really have to start at the beginning and work backwards until you locate
the problem.

A pegged gauge can generally be traced to a short in the system.

1. Locate the sending unit in the tank.  It is under the carpet in the rear
of the car opposite the spare.  There is a black plastic cover, often under
a white piece of fireproof insulating material, that can be pried up.
2. Remove the wire plug attached to the unit.  If the gauge returns to empty
then the problem is in the sending unit - an internal short in the wiring of
the unit itself.
3. If the gauge is still pegged, then the problem is in either the wiring or
the gauge.
4. Disconnect the wiring harness at the pod.  This will make the gauge go to
empty along with everything else.
5. Find the sending wire on the sending unit.  There is a wire from the
gauge and a ground.  There is also a wire for the fuel light.  Check the
wire to the unit with an Ohm Meter.  If it is a dead short to ground then
there is a short in the wiring.  Somewhere the wiring harness has chafed and
is contacting the chassis.  This may take a little driving to make the
contact as the insulating is just getting worn off and may even need a
little heat to make a ground contact. Remember on German cars Brown is
Ground.
6. If there is no short in the wiring then the problem is with the pod.  To
fix this you will have to pull the pod.  The most likely case will be a bad
circuit board on the back of the pod or the gauge itself.  The pod
connections can be cleaned up with an eraser and this may be all it takes -
but with an 82 I would not count on it.  You can test the gauge separately
by rigging up some wiring to the tank unit, but you have to be careful.  If
the gauge unit tests out good then the circuit board has some bad
connections.

My best guess - you have some corrosion on the connection to the gauge.
DEVEK has replacement pod circuit boards - doing this is worth the effort.
I think have a gas gauge laying around some place if you need one.

Hope this helps.

Dan B.