I need help!

[davis5429]

I can't seem to figure out how to fix my fuel guage in my 1986 chevy s10 It didnt work right when I got it it had always read to about half full when full and then worked accordingly from there but I recently had a fuel pump failure and a bad gas tank so I upgraded the fuel tank and a new assembly to a 20 gallon from rock auto and it just doesn't read accurately at all (I thought the problem was more than likely a failing sending unit causing it to read incorrectly) so it's been a month since that and I still can't figure it out can someone please help!