Fuel gauge

[angus121]

With how expensive fuel has become I haven't filled up completely in a long time just up to half a tank at a time but never completly full.and just recently I bought a ts chip and run it through a quarter tank and it went through that much normally so I decided to fill the tank completly to check my mileage, and as soon as I did that my gauge seems to never be right I went 20 miles it said I used a quarter tank then I parked it and it filled back up and if I shut it off and turn the key on and off it shows different amounts of gas but never were it should be..so idk if something messed up when I finally filled it up and confused it or if my chip might be faulty or if it's something else I'm not thinking off...I've been driving it easy and I even run the chip on stock and all through the positions to check that and it's just not right..so anything would be helpful thanks and sorry for the lack of punctuation i forget to do it on my phone