Gas gauge not working properly why?

I replaced my fuel pump yesterday and now the gauge barely shows any gas in the tank. I know there is at least fifteen gallons because I drained the tank to make it easier to reinstall. The gauge worked fine before the swap. I replaced the wiring pigtail like the instructions said but they didn't say to install the supplied fuse. It reads a little as long as I keep fifteen gallons in it but would like to use the hole tank without the guesswork. Thank you in advance for any assistance anyone can provide!

Fuel gauge would operate between "1/2" to past "full", so I changed pump/sending unit about 45 days ago.

Gauge is now stuck at "empty" no matter the actual fuel level.

Disconnected sending wire (purple) at firewall, put it to ground, turn 'on' the ignition and gauge went past 'full' to about the 3 o'clock position.

Tested the sending wire also back to the tank, it came back at 5 ohms.

Started the engine, fuel gauge went back to 'empty'. It moves between 'empty' and '1/4' when the ignition is off.

Fuel gauge stays in full position.

Put in new fuel tank and sending unit now gas gage bounses when moveing. Tested gage and wires.(Ok)replaced sending unit with three different ones. Now has factory ac delco sending unit and stiil has the same problem. Any ideas? Please help.

"anddgtea "the gauge bounces up and down if tank is not full with any movement of the truck and key is on. Could it be somthing with the tank?

I got a 94 Silver ado and the fuel gauge didn't work when I got it I was driving and it magically started working again and a couple days later it quit working again while Ur driving but when I turn the truck off the gauge jumps up a ill bit but when I hit the breaks the gauge goes all the way back down to empty again what could be all of the possibilities of what could be wrong I am not mechanically inclined so I really don't know what it could be

Hi I want to install a Fuel Level Gauge. My cluster fuel Level gauge does not work. How would I install a Fuel Level Gauge? Where would I run power from to make it work. This is what I am looking to install. Thanks.

This is what I am looking at.

Hi mine reads high past the f on the cluster after 100 miles it starts to move and then when I am at 1/2 a tank and I am sitting in traffic or at a light it goes down into the yellow and when I start driving again it goes up to half a tank their was one time it showed I had a half a tank and I only had 5 gallons in the tank. I had the fuel pump replaced. That fuel pump worked started driving it 7 months later I kept complaining it kept cutting off. The shop that put the new fuel pump in it said it was not the problem. So I took it to a friend and he recommended I buy a new throttle body. I was not convinced. So I bought it put it on and had the same problem. So I had bought a new fuel pump and fuel filter. He took the fuel filter off and said rust was coming out of the line. So he replace the filter and fuel pump. He said the tank was rusted but I needed too see what was going to happen. It kept doing the same thing it was stalling and dying. So I bought a new tank and got a new fuel filter and fuel pump. So I know it's not the sending unit. I also had bought a new fuel pump relay. I tested the cluster fuses and it had power. I also changed that fuse out and it made no difference. Thanks.