Could be either, could be pump on its way out too.
I ran out of gas bringing my wagon home for the first, ended up being a bad sending unit, pulling air. Another frequent culprit are the hoses going from the sending unit to the hard lines on the frame, they become brittle devoloping cracks. I belive by 86 they added an access panel under the rear seat for the sending unit.
"I like fun" Edd
Clawed: 90GW, TFI, Streetfire, 3"lift all spring, working RKE,
Edel2131, Holly 1850, mild cam (105º) 13mpg for now.
"Its a Jeep thing, and I still don't understand"
05 Renegade OME 927, 947, top plate, JBA 4.5s ,ST/MAXX 245/75/16