Re: Fuel Gauge problems, same as Sean's temp guage...

[Huw Powell <human@nh.ultranet.com>]

> I have a fuel gauge in my '82 100, that has identical symptoms as Sean
> Ford's temperature guage/multi sensor problem.  It often works, but quite
> often reads a lower than true reading.  It seems to work best when I have
> been going down hill, or have just done a long brake from high speed.  It
> also sometimes recoveres when at idle, and you can see it drop as you
> accelerate!
I stayed out of this due to radical model differences, but if it is any help...
on my 82 coupe the fuel and temp gauge both work the same way.  A regulated 10
volts (created *only* for those two gauges is fed to one side of the gauge, the
sender is connected to the middle and presents a varying resistance to ground,
and the gauge is grounded as well.  My temp gauge was wierd after my dashboard
r/r, reading low, consistently.  This implies a higher resistance in the gauge
to sender wiring.  After it went away all I could figure is some bit of crud
(shaved plastic?) got into the inst cluster connector and had a fixed resistance
in the 200 ohm range.

You can test the gauge with a fixed resistance to ground, bentley kinda gives
the values, you can test senders in pans of water you heat up (as with
thermostats), so long as you know the target resistances.  Mine were (I think)
about 450 ohms cold down to 70 ohms hot.  50 ohms is overtemp but still on
scale.  I suspect in my car at least that a similar fuel gauge fault could
arise.  fingers crossed.

hth
-- 
Huw Powell
HUMAN Speakers
79,80,81,*82*,83,84,85,86,87,88,97 Audi Coupe (GT)...