My daily drivers fuel gauge has worked well for about 8 years. It, however has not been going to full for about 6 months. It does seem to be accurate when the tank is near empty. The low fuel light, has been inaccurate for a couple of years. Most of the time the light is on , even when the tank is full.
So, yesterday I did some investigating.
When I disconnected the fuel leval sensor wire in the trunk, the gauge went all the way to full, the low fuel light remained on.
When I grounded the sensor wire to the gauge, the fuel gauge was on empty, low fuel light still on.
Soooo, I don't think the problem would be in the tank, or a bad sender ground, any of those problems would send the gauge even further to the full mark.
I pulled out the gauges, these are ones I found 8 years ago from a 1969.


http://s173.photobucket.com/albums/w67/dale68z/?action=view&current=whitecamaro012.jpg
Here is the back of the fuel gauge

http://s173.photobucket.com/albums/w67/dale68z/?action=view&current=whitecamaro008-1.jpg

I found the black wire (the one that goes to the left side in the picture) on the bottom of the gauge was loose, the black that goes to the low fuel module was tight. Red, green, black, and yellow are the low fuel module.
I put it all back together, and the gauge seems to work well.
We filled the tank and went out cruising central ave for the night.We went through about 1/4 tank of fuel. And what do you know the low fuel light is also out!
Some other pictures of the back side of the gauges
http://s173.photobucket.com/albums/w67/dale68z/?action=view&current=whitecamaro016.jpg

http://s173.photobucket.com/albums/w67/dale68z/?action=view&current=whitecamaro018.jpg

http://s173.photobucket.com/albums/w67/dale68z/?action=view&current=whitecamaro017.jpg

http://s173.photobucket.com/albums/w67/dale68z/?action=view&current=whitecamaro020.jpg

Grounding the wire should give you empty and an open wire will show full. The tank sender should give you 90 ohms of resistance when full and near zero ohms when empty. So your statement about connecting the sender wire and making it show more than full is incorrect.

It sounds to me like your guage and wiring are OK. Next step would be to get a potentiometer that you can set for 1/4=22 ohms, 1/2=45 ohms, 3/4=68 ohms and 1/1=90 ohms give or take. If that all checks out, your sender may be at fault.

I encourage you to explore the stickies at the top of the Electrical forum. Jim M. has posted a lot of useful troubleshooting guides for gas gauge issues that should help.

So your statement about connecting the sender wire and making it show more than full is incorrect.

If that is what I said, you are correct, I'm wrong
The point of this thread was to tell you and anyone willing to listen how I fixed my car.
My car is fixed. I'm not looking for help, just sharing information, with pictures.
It seems there are alot of posts on how to install or fix gauges. They really are simple. Simple things, like what I found are usually the cause of a problem.
BTW, took the car to Cabellas this afternoon, low fuel light is on with 3/4 tank on the gauge, so that sucks.
Dale

OHhh ohh ohh....my bad. Sorry. I must have been in my mode and wasn't paying attention.