Gas gauge solution?

[Isaiah92260]

So my gas gauge isn’t working, when the key is off the needle goes down to around 3/4 a tank, but once I turn the key, it shoots way past full where I can’t see the needle. I’m assuming the gauge isn’t working since it is showing that it’s moving when it gets a signal, messed around with the wires and seems like they are working since the needle is getting a signa and when I ran I test light the power wire at the gas tank it lights up, I even replaced the ground wire at the gas tank and still nothingl. I’m thinking the wiring could be grounding out somewhere? Or maybe the float inside the tank has gone bad?