Fuel gage goes from full to emty all the time. when it first stated it only did it with quater tank or less.

Yes the fuel tank has to come out to change the fuel pump. But are you sure that is the problem ? Your vehicle has a Fuel Pump Flow Control Module (electronic's ) Or is it just your fuel level sensor you want to replace ? And to your question of if the fuel level sensor is bad will the car shut down if the gage says it is emty but it is not? No ,this will not shut down the vehicle. You probably have no idea of the complexity of the electronic's involved an the thing's that can cause the gauge not to work .
Fuel Gage
The instrument panel cluster (IPC) displays the fuel level as determined by the ECM. The IPC receives a serial data message from the ECM indicating the fuel level percent. The fuel gage defaults to empty if:
• The ECM detects a malfunction in the fuel level sensor circuit.
• The IPC detects a loss of serial data communications with the BCM
• The BCM detects a loss of serial data communications with the ECM
When the fuel level is less than a pre-determined value, the low fuel indicator illuminates in the IPC.
Unless you have a factory or professional type scan tool your better off taking your vehicle to a qualified repair shop.

Fuel Gage Inaccurate or Inoperative
Circuit/System Description
The fuel level sender changes resistance based on the fuel level. The engine control module (ECM) monitors the signal circuit of the fuel level sender to determine fuel level. When the fuel tank is full, the sender resistance is low and the ECM senses a low signal voltage. When the fuel tank is empty, the sender resistance is high and the ECM senses a high signal voltage. The ECM uses the signal circuit of the fuel level sender in order to calculate the remaining fuel level percent in the tank. The ECM sends the fuel level message via the serial data circuit to the body control module (BCM). The BCM sends the fuel level percent to the instrument panel cluster (IPC) via the serial data circuit for display on the fuel gage.

Circuit
Short to Ground
High Resistance
Open
Short to Voltage
Signal Performance
Fuel Level Sensor Signal
P0462
1
P0463, P0464
P0463
P0461
Fuel Level Sensor Low Reference
--
1
P0463, P0464
P0463
P0461
1. Fuel Gage Inaccurate or Inoperative

Do you know what a DTC is ? diagnostic trouble code !

the fuel sender has gone bad. you will have to remove the tank and replace it

You have a bad fuel level sensor.The fuel tank needs to come out and the sensor replaced.You don`t have to replace the pump assembly.You can get the level sensor separate.I`m not sure if the parts stores have it but I know the dealerships do.Hope this helps.Good luck.

If the reset does not work, you may have to inspect the float device inside the tank that goes up and down along with the fuel inside the tank. It may not be aligned or needs replacement.

sounds like you need new fuel pump. fuel pump located in gas tank. before you go buy a new fuel pump first push up and down on trunk of car real hard to try to dislodge the little armature inside of tank. this little armature is what sends the signal to the gauge telling you the quantity. push up and down on truck to try to dislodge small signal armature then check your quantity. try this when you are having the problem and i am willing to bet the little armature is stuck. the only way to fix is to buy a new pump.

either the fuel sender in the gas tank is bad or the bcm is bad,most likely sender

Could be a fuse - but often is a plug pulled off the fuel tank level sender - look at the top of the fuel tank.

There could be two problems here:
1. That buoy floating tank is not working properly
2. That the electrical system that fails to submit the dashboard.

Review this information:
- ZJ-Secc-8E-Instrument-Cluster-and-Gauges
Page 2 - Fuel Gauges description
Page 4 - Voltimeter/Tachometer/Fuel Gauge/Low Fuel Inoperative
Page 10 - Specifications
- ZJ-Secc-14-Fuel-System
About Fuel Tank components
- ZJ-Secc-8W-Wiring-Diagrams
Fuel Tank and Gauge & Sensor Units Sending (Page 93 and next)

Good luck... and remember rated this help.

it sounds like the level sensor on the sender (fuel pick up pipe in the fuel tank) is getting stuck. the level sensor is a float that is attached to the sender, and you will need to remove the fuel tank to get to it.

hope this helps.

THIS PROBLEM IS CAUSED BY A DEFECTIVE GAS GUAGE SENDING UNIT, U WILL NEED TO PULL THE FUEL TANK AND REPLACE IT.