Fuel Gauge stuck

The sensor in the gas tank is faulty, the fuse has blown or the gauge at the dashboard side if faulty - try disconnecting the wire attached to the gas tank end and ground it - if the gauge should indicate a full tank - if so then the float unit in the tank need replaced - if it doesn't move then it is either the fuse or the guage.

The most common way to find out is to test both components.
The sending unit in most vehicles grounds the gauge on the dash.
You would unplug the sending unit - pump harness at the tank and ground the sending unit wire. If the gauge climbs up to full the sending unit is at fault.
You could also measure resistance in the circuit in the tank when the tank is close to empty and after filling it up. The resistance should be different each time.

You don't give the make model and year, but generally the gauge is controlled by a float in the tank. The gauge could be faulty, or the sending unit with the float in the tank.
When the gauge reads empty and you know you have fuel in the tank, a mechanic would check the connector at the tank for power and ground.

Hello graytape, was the fuel gauge and low fuel light working and then one day just stopped working?, if so, you have probably blown a fuse and you should be able to locate what fuse and where it's located in the owner's manual.
If you recently got the vehicle and then you found out that the gas gauge and low fuel light doesn't work then that is something completely different.
without knowing the year of the vehicle I can only give you an educated guess.
Many vehicles have a float in the gas tank and this float is directly linked to what you see on the gas gauge. However, after a number of years the floats get saturated from the fuel and become heavy, heavy enough to where they don't float anymore. That is one of the most common causes of the fuel gauge not working.
The sensor that activates the low fuel warning light may be independent of the fuel gauge and the fuel in the tank isn't low enough to turn it on. Your tank has to be very low to activate the low fuel warning light.
Good luck!

Fuel gauge float in the FUEL tank seems to be misaligned or already damage! Bring it to ur nearest garage mechanic to take a look at it! Taaah!

i think that the problem you face is due to your fuel gauge more than the battery .
the fuel gauge at full tank can be running out of sensor due to faulty gauge mechanism . i would not worry too much as this is common even in cars .
My advise to you is not to over fill your tank and this will resolve your problem .

Definitely the gauge can be changed, provided the float in the fuel tank is OK, i.e. no leaks. This float connects to a potentiometer which records the current flowing thru it and displays it in the gauge. So before replacing the gauge measure the current and match that against the quantity of fuel in the tank...............sodeep

the fuel level sending unit has been incorporated into the fuel pump assembly.
the fuel pump is most likely your problem, these pumps dont like fuel additives so be careful.
most common problem with these fuel gauges is the sending unit, the sender contacts will errode over time fuel additives seem to speed the process.

replace the fuel pump assembly

hope this helps