[T3] Fuel gauge issues (jumpy needle)

[Jacob Adam Schroeder]

Also, I saw the fix that somebody shared previously about drilling a hole
in the center of the sender.  That was interesting but I'd prefer not to
make that mod if I can avoid it.

On Thu, May 28, 2015 at 3:58 PM, Jacob Adam Schroeder <
jacob.schroeder at gmail.com> wrote:

> I have a 1972 Squareback and have been having a recent issue with my fuel
> gauge.  I recall the the gauge used to work, so I am not sure what has
> changed over time.
>
> The gauge appears to be accurate, when it is steady.  But the problem I
> have is that the needle jumps around like crazy (especially when I am
> driving).  From looking at the gauge, it appears that there are two ground
> points: (1) through the housing to the spring clips to the dash, and (2) a
> ground wire to the back of the gauge through the black plastic piece that
> clips on to the rear of the gauge.
>
> Are these grounds redundant in that only one has to be good?  Do both
> grounds service the fuel gauge or is the wire for the lights and the fuel
> gauge grounds through the clips?
>
> The bouncing needle to me indicates a grounding problem, but I cannot seem
> to track it down.
>
> Also, I followed the test in Bentley--disconnecting the sender and
> grounding the wire to the sender housing, and the gauge reads full.  So,
> according to Bentley, the sender is good.  I tested a spare sender and get
> the same jumpy needle.  So I am fairly confident my sender is OK.  But, do
> the late (1972) sending units need a tab of exposed metal on the tank for
> grounding?  I saw something to that effect in Bentley and I did repaint my
> tank within the past few years, but did not leave a portion of exposed
> metal along the circumference of where the sending unit mounts to the tank.
>
> Also, could be unrelated, but I also get an intermittent fast turn signal
> blink that may share a similar cause.
>
> Any help would be appreciated.  Thanks,
>
> Jacob
>
>
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