In your profile, it says you have a 4.0 in your '83 CJ. The 4.0 was offered in various configurations from '89-'05 or so. They were all fuel injected, and the vehicles they came from used different fuel sending units than the stock CJ. CJ's sending units were 10 Ohms when full, 73(ish) when empty. Fuel sending units from '91 on were 20 Ohm full, 270 empty.
If your 4.0 conversion included the fuel tank (or just the sending unit) from the donor, that sending unit is not compatible with the stock CJ fuel gauge.
Here's a link with further trouble shooting advice.