Fuel Gauge 1999-2003 GM Vehicles

Could be the gauge in the instrument cluster ! There are videos on youtube on testing fuel gauge .
Repairing Fuel Gauge Problems 2004 Mercury Marquis EricTheCarGuy

How to test fuel gauge tank sending unit P0463 GM

You don't say what make , model an year vehicle . Testing before replacing parts is the way to a proper fix .

Spencer, Check all fuses ,plugs and grounding at the tank.The sending unit module, inside the GM's gas tanks were notorious for going bad in this err, when you changed it did you use a quality part? Also the fuel pump sending unit plug/wire harnesses were known issues, so much that replacement pumps would often come with replacement plug to splice into existing harness. Check the attached links,instruction and guides on how to trouble shoot fuel gauge/sending unit, Good luck
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Check fuse, if fuse ok, then you need to check the fuel gauge at the tank. most probably there's a loose connector or the gauge is faulty

no, sorry. Here are the R&R instructions from autozone.com:

The following procedure requires the use of the GM Fuel Gauge Sending Unit Retaining Cam tool No. J-24187 or equivalent.


CAUTION Before removing any component of the fuel system, be sure to reduce the fuel pressure in the system. The pressure regulator contains an orifice in the fuel system; when the engine is turned Off, the pressure in the system will bleed down within a few minutes.

1. If the fuel system has been in use, turn the ignition switch to OFF and allow the system time to reduce the fuel pressure.
2. Disconnect the negative battery terminal from the battery.

Be sure to keep a Class B (dry chemical) fire extinguisher nearby.


CAUTION Due to the possibility of fire or explosion, never drain or store gasoline in an open container.

1. Using a hand pump or a siphon hose, drain the gasoline into an approved container.
2. Raise and support the vehicle on jackstands.
3. Support the fuel tank and remove the fuel tank-to-vehicle straps.
4. Lower the tank slightly, then remove the sender unit wires, the hoses and the ground strap.
5. Remove the fuel tank from the vehicle.
6. Using the GM Fuel Gauge Sending Unit Retaining Cam tool No. J-24187 (or equivalent) or a brass drift and a hammer, remove the cam locking ring (fuel sending unit) counterclockwise, then lift the sending unit from the fuel tank.
7. Remove the fuel pump from the fuel sending unit, by performing the following procedures:
   1. Pull the fuel pump up into the mounting tube, while pulling outward (away) from the bottom support.
   
   

When removing the fuel pump from the sending unit, be careful not to damage the rubber insulator and the strainer.

1. When the pump assembly is clear of the bottom support, pull it out of the rubber connector.

To install:

1. Inspect the fuel pump hose and bottom sound insulator for signs of deterioration, then replace it, if necessary.
2. Push the fuel pump onto the sending tube.
3. Using a new sending unit-to-fuel tank O-ring, install the sending unit into the fuel tank.

When installing the sending unit, be careful not to fold or twist the fuel strainer, for it will restrict the fuel flow.

1. Using the GM Fuel Gauge Sending Unit Retaining Cam tool No. J-24187 (or equivalent) or a brass drift and a hammer, turn the sending unit-to-fuel tank locking ring clockwise.
2. Install the fuel tank, align the insulator strips and install the strap bolts. Torque the inner fuel tank strap-to-vehicle bolts to 26 ft. lbs. (35 Nm) and the outer fuel tank strap-to-vehicle nuts/bolts to 26 ft. lbs. (35 Nm).
3. Connect the fuel lines.
4. Connect the negative battery cable, start the engine and check for leaks.
5. Lower the vehicle.

Fairly common problem with GM vehicles. The sending unit in your tank has a small circuit board that an arm is attached to which moves up and down according to your fuel level. This circuit board and arm are not making good contact. Unfortunately the only good solution is to replace this part.