2000 chevy with code p0463

2000 chevy 1500 pick up 4.8 108000 miles fuel level circuit sensor high voltage whats that mean
It means there is a problem in the fuel sending unit circuit. The PCM uses a 5v reference on this system to calculate fuel level. There is either a problem in the sending unit or related wires causing the voltage to be too high for too long.

I'm assuming the fuel gauge isn't working.........
the gauge is not working right would that send a p300 code also?
No, a P0300 is a random misfire.

I would take a fuel pressure reading and see how long the pressure holds with the key off. You should have around 60 psi KOEO and the pressure shouldn't drop too much too fast.

If the pressure is weak & drops too fast, I would start with changing out the fuel pump & connecter. These come as an assembly, pump, sending unit & FTP sensor. While it was out I would verify the 5v ref & grounds. If I remember correctly the fuel gauge ref wire is the small purple wire. The ground wires are black.

It's quite possible this may take care of both problems.



Just a quick caution to never use a test light on a computer ref voltage line. It's very possible to damage the PCM that way. High impedance voltmeter or lab scope only.