A #16 AWG will work.
The fuel gauge is a very simple affair. The gauge itself, a 3 terminal voltage regulator and the in tank level sensor. Check fuses first, check for a good ground to the fuel gauge sensor on the tank. Pull the wire on the tank sensor, ground the wire, with key on gauge should deflect. No gauge movement means bad gauge or regulator. Reconnect wire. Check for 12V at the input of the voltage regulator, check for around 5V at the gauge side of the VR. If no suspect bad VR. If yes suspect bad gauge. If gauge does deflect when grounding tank sensor wire the intank sensor is bad and must be replaced.
your gas gauge float is in the gas tank you have to drop your gas tank and take out sending unit but if the gas gauge is not reading right you should check the ground wire on the gas tank
Float could be stuck in the tank or the ground wire on the tank is broke.
Your sending unit in the fuel tank may be bad, the wire connector could be disconnectged or there is a broken wire in the circuit, or the gauge itself has an issue.
The gauge could be bad, the fuel gauge sending unit in the gas tank as part fo the fuel pump could be bad you could have a bad ground wire you could have a broken wire in the harness runnign from the fuel tank to the gauge.
fuel sending unit broken wire or gauge is bad
Either the sender wire is bad, or the sender inside the fuel tank is bad. Here is how to test it. Ground the wire that runs from the tank. This should pin the gauge all the way to full. If this happens, it is the sending unit. No gauge movement means bad gauge. Remember to turn on the key while testing.
GAUGE IN DASH OR ITS VOLTAGE REGULATOR IS BAD. WIRING OR CIRCUIT BOARD. UNIT IN TANK. FLOAT IN TANK HAS SUNK. dISCONNECT GAUGE AT TANK AND GROUND THE WIRE-THAT SHOULD CAUSE GAUGE TO GO TO FULL HOT. MOST CAR GAUGES WORK THE SAME WAY.
The size of the wire is stated by its gauge under American Wire Gauge. Six gauge wire is size 6 AWG.
Wire gauges are defined in such a way that the lower the gauge, the thicker the wire. So, 8 gauge wire is thicker than 10 gauge wire.
wire of the unit on top of gas tank or fuse blown
The gage is broken or the wire is broken or the sensor in the tank is broken or the fuse is blown.