Common problem for rodeos in fact there was a tech bulletin put out for problems with the sending unit but no recall issued. So i think you will need to replace the sending unit in the tank
More than likely the fuel gauge sending unit located in the fuel tank is faulty.
on my 99 rodeo, this problem was caused by the fuel indicator located inside the fuel tank and part of the pump - you need to replace the entire pump which entails dropping the entire tank
check ground on fuel tank
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.
a bad ground
check the power to gauge and the temperature sensor (tps). if no power broken wire or short to ground. if power to both areas bad gauge.
No oil pressure - after checking with a manual gauge
Not always. You could have a conduit with 10 pairs of 14 gauge wire - not every wire in that bundle are going to be ground. Ground is usually identified as having a green coating on the wire ... sometimes it is just bare copper strands or a solid copper wire.
you drop the fuel tank and replace the sending unit
Float could be stuck in the tank or the ground wire on the tank is broke.
You may have a bad ground in that case, the ground is at the top of the gas tank or the float inside the gas tank could have sunk or got stuck. Check your wires going to and from it not have a power or ground could do it as well.
Either the sending unit in the tank quit, orthe fuse blew, if the gauge is at the extreme empty or full, that could be a faulty ground somewhere on the system