A few days ago I am running off of my rear tank in my 97 and when i get to a 1/2 tank the gauge needle starts going up almost to full then back down and all over the place randomly. I filled up and it stopped until i got to the 1/2 tank mark. what is going on?

 

check yer wiring as you may have a bad connection

 

i'm betting on a sender with what you're telling us. here's the facts on your gauge:

With the sending unit float arm in the empty stop position, resistance should be 15 ohms (below E). With the sending unit float arm in the full stop position, resistance should be 160 ohms (above F). The fuel gauge should read empty at 22.5 ohms and full at 145 ohms.

basically, next time this is happening, unplug the fuel sender at the tank. if it goes to full or empty then it's most likely your fuel sender. if it stays the same then it's most likely you gauge.

you caan also check you gauge by applying different resistors to the sender circuit wire. change the resistance ant the gauge should follow.