Sounds like you have a bad quantity sender.
John Strenk is the master of troubleshooting Jeep CJ gauges. Here is a link to his site that explains the values your should see at the sending unit.
John's work has helped me numerous times.
'86 CJ7, 258, Carter BBD, Nutter'ed, TeamRush'ed, T-18, Twin Sticked Dana 300, D30 Frt-Pwr Lok L/S-4.10, AMC 20 Rear-Mosers-Detroit Locker-4.10, 2.5 BDS Lift, 1" Body Lift, 33" Wild Country M/Ts, Black Spoke wheels
'45 CJ2A, L134 Go Devil, T-90 Tranny, Warn O/D, T-18 T-Case, Dana 25 Frt, Dana 41 Rear, 531st CJ made
My 401 build: [url]http://www.jeepforum.com/forum/f8/trapshooters-401-build-1338277/[/url]