Weird gas guage

ok so my 96 SOHC neon is slowly getting its problems fixed. last night replaced the exhaust gasket flange to get rid of the weird sound when accerating (such an improvement :D). now it think its time to figure out the gas gauge. ok so whenever i get gas (fill her up) it goes to full. then about 20 miles down the road it drops to 1/4 tank or empty and stays there till i get gas again. sometimes when i start it the gauge will jump up to where im pretty sure it should be (3/4 tank with like 150 miles on trip o.) but drops almost instantly. ive resoldered my gauges and they all work except the gas gauge. it worked okayish untill i got my tank replaced a few years ago and ever since has been weird. i also tried adding some gunk remover like gumout and lucas and all they really achieved is giving me better gas mileage :) any ideas?

Probably a bad fuel sending unit. It is located in the gas tank.

ok easiest way to do that without wasting a lot of gas (with gas at 3.30 dont need to be spilling quite a bit on the ground) and im guessing its part of the fuel pump and to replace it takes replacing the whole works right?

The fuel gauge sending unit (fuel level sensor) is attached to the side of the fuel pump module. The sending unit consists of a float, an arm, and a variable resistor (track). The resistor track is used to send electrical signals to the Powertrain Control Module (PCM) for fuel gauge operation and for OBD II emission requirements.

Its enough trouble to work on the fuel pickup assembly that I would replace the entire unit; and not have to worry about it for another decade. However if you are really energetic, you might be able to get just the fuel sender parts from a salvage yard. The salvage yards in different states may have some annoying requirements about letting you get parts from fuel tanks though.

ok yea maybe ill snoop around some salvage yards and see if i cant find some parts. it might just be easier to get gas at the end of each week.