Gas hand reads full all the time

If the fuel pump and fuel gauge sensor shares the same housing as is often the case - maybe the person that fitted the pump damaged the sensor or float...
Alternatively it could be a wiring or connector problem, defective gauge or printed circuit.

you have a float arm in the tank that rises when you add fuel I think its called the sending unit in the tank with fuel pump. it could be getting defective or it could be you fuel hand gauge going defective.but biggest part of time its the sending unit in the tank, hope this helps

If he told you the fuel pump would correct the fuel guage, take the car back and make them fix it under warranty. I have been in the auto repair business for 21 years and if I mis-diagnose a car, I have to fix it for free to keep the customer happy.

if it worked for a short period of time after doing the pump/sending unit the check the connections going to the pump/sending unit they would have been moved around doing the pump

Something wrong with the pickup tube on the pump.

Dont we wish it be full all the time but gas in it. Okay for the sending unit reading full its getting a full ground reading,Key on engine off. does it move and goe down. It should if it doesnt the problems with the gauge itself. 2 test disconnect the wire harness, did the gauge go down. the problem will be in the sending unit can be a hung float(Rare).

Assuming nobody stole all of your gas, the fuel level sending unit is bad, the wiring to it is bad, or the instrument panel is failing.

The wiring can be accessed inside the trunk, on the left side, by pulling the carpeting up. The sending unit should read about 35 ohms when full and 235 ohms when the tank is empty. My Haynes manual says the wires are Purple, and Black-White.

If the sending unit reads correctly then the wiring to the instrument panel, or the panel itself is malfunctioning.

If it is the sending unit: the sending unit is attached to the fuel pump inside the fuel tank. You must remove the fuel tank to replace it. While you are in their you might as well put a new fuel pump in.

Most likely it a bad fuel level sensor on you fuel pump. You will have to replace the fuel pump as that is the only way to replace the sensor for you fuel gauge. The sensor is built into the fuel pump. The contacts on the sensor become corroded over time and cause the sensor to malfunction causing your fuel gauge to read full all the time. I have a 2001 Montana extended version that had the same problem. In order to know when I needed to fill the tank, I would completely fill it each time I put fuel in and reset my trip odometer. I would go 400 miles on the tank before I would refuel until we were able to replace the fuel pump.

The gas guage has a sending unit in the tank attached to the pump, there is a small circuit board on it that has smal"fingers" that send the signal to the guage.These get worn off and thus sends a false reading to the gas guage in the dash. The gas tank must be removed and a new unit put in to solve the problem. I had to do this repair to mine. As for the gas issue, just try pulling the nozzle back out of the filler neck when putting gas in, sometimes the overflow tube gets plugged up and won't allow the air to escape as the gas goes in the tank, making the gas pump think the car is full, pulling the nozzle will allow the air to escape. Hope this helps.