you will have to drop the fuel tank and remove the pump gauge unit. it maybe stuck, broken wire, or simply bad.
Either the wire from the gauge to the sender is broken or the sender is bad.
The gage is broken or the wire is broken or the sensor in the tank is broken or the fuse is blown.
fuel sending unit broken wire or gauge is bad
The temp sending unit may be unplugged or faulty.
If the fuel gauge is stuck, the needle never moves, then the gauge has a problem and needs to be replaced.
check for broken wire from fuel sender unit in fuel tank to gauge. check fuel sender unit for proper operation. float may be stuck in the tank then check fuel gauge
Could be, low on coolant (a leak in the system), a stuck closed thermostat, a faulty temp gauge sending unit, a bad head gasket or cracked head (worst case scenario).
Most of the time it's the fuel level sender in the fuel tank if your gauge moves around a bit but doesn't read correctly. If the Gauge is stuck on full all the time, the gauge itself is broken.
The fuel gauge on a Chevy may become stuck if the sending unit is defective or become disconnected. Without a signal from the tank, the gauge will not move.
either the fuel gauge needs replacing or the fuel gauge sending unit in the fuel tank is stuck
The float is stuck down at the bottom of the tank or you could have a wiring problem.
temp gauge is stuck on hot