I posted this twice a ways back but no one gave any advice on what the problem could be. Here's the post again and please note on the bottom that the sending unit has been replaced:

While driving, no matter how slow or fast, if I hit any bumps or brake/accelerate the fuel gauge is all over the place. Not the normal GM float, I'm talking erratic movement. While cruising on a smooth road the needle will move just a little at random. Once I stop for a minute and sit still it will settle down and read correctly.

I have a new sending unit in the car and it does the same thing as it did with the old one. Any ideas?

 

First thing I would do is test weather it's the sender wire grounding, or the gauge.

You'll need to test with an Ohm's meter the wire coming from the sender while driving. It's normaly a pink wire. I know it's going to be fun finding it, but it's mounted under the dash on the left side, or maybe you can get a reading on the gauge itself.

It should read between 0(Empty) and 90(Full) Ohm's.
If your readings are all over the place, then I would start tracing a ground problem. The funny thing is, if the wire grounds the needle on the gauge will show empty, and if the curcuit is open it will pegg beyond full.

If your reading bounce around only few ohm's I would take a hard look at the gauge.

I'll post some pictures latter tonight.

Ron

 

Pic #1

 

On this one you can see that most all electrical from the rear of the car runs threw this area.

Pic #2

 

Thanks for the pics, I'll check it out soon. My interior is totally out right now for some chassis work so all the wires aren't to hard to get to.

 

Anytime ...

Hey, not sure what year you have, but those metal contact that are laminated to the plasic sheet behind the gauges begin to were out. Might be another area to investagate.

Ron