Gas gauge not working

Hey everyone,
I was trying to diagnose what might be causing my gas gauge to not work. Ever since I received the car my 88 dippy,the gauge has not worked. I had to drop the gas tank months back and replaced the pickup and sending unit. After this the gauge still hasn't functioned. Is there a common problem or issues on our cars that cause the gauge not to work? I'm not that good with chasing down electrical gremlins. I have another gas gauge that I can throw in to see if its just that but...

Gas gauge not working
Author: 88_AHB