Copied from a post made by BowTieTech. Original post below:
https://montecarloforum.com/forum/mo...15/#post114938

This procedure for fuel pump module or fuel level sensor replacement applies only to 2000-2004 Monte Carlo's. By the way,the driver information center in the overhead console relies on data from the fuel level sensor along with several other data inputs to make it's fuel information calculations.If the fuel level sensor data is skewed the driver information center display will be inaccurate. The artwork depicting the location of the access panel under the trunk carpet is rather poor,but the location is very obvious once the carpet is removed.
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Fuel Sender Assembly Replacement [/align]
Removal Procedure
Caution:Fuel Vapors can collect while servicing fuel system parts in enclosed areas such as a trunk. To reduce the risk of fire and increased exposure to vapors: [align=left]



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Use forced air ventilation such as a fan set outside of the trunk.[/align][align=left]



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Plug or cap any fuel system openings in order to reduce fuel vapor formation.[/align][align=left]



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Clean up any spilled fuel immediately.[/align][align=left]



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Avoid sparks and any source of ignition.[/align][align=left]



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Use signs to alert others in the work area that fuel system work is in process.[/align]

Notice:Clean all of the following areas before performing any disconnections in order to avoid possible contamination in the system: [align=left]



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The fuel pipe connections[/align][align=left]



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The hose connections[/align][align=left]



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The areas surrounding the connections[/align]

Important:For rear compartment (trunk) accessible fuel sender assemblies, completely remove the rear compartment carpet before removing the fuel sender access panel.
Important:Always replace the fuel sender O-rings when reinstalling the fuel sender assembly.
Important:The modular fuel sender assembly will spring-up when the snap ring is removed.
Important:Always maintain cleanliness when servicing fuel system components.
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Relieve the fuel system fuel pressure. Refer to Fuel Pressure Relief .
Remove the rear compartment trim panel. Refer to Rear Compartment Trim Panel Replacement in Body Rear End.
Remove the fuel sender access panel nuts.
Remove the fuel sender access panel.
Disconnect the fuel tank pressure sensor electrical connector.
Disconnect the fuel sender electrical connector.
Clean the fuel pipes, and fuel sender assembly to prevent possible fuel contamination during removal.
Disconnect the quick-connect fittings at the fuel sender assembly. Refer to Plastic Collar Quick Connect Fitting Service .



Remove the fuel sender retaining ring.
Remove the modular fuel sender assembly.
Clean the fuel sender assembly O-ring sealing surfaces.
Inspect the fuel sender assembly O-ring sealing surfaces. [/ol]
Installation Procedure
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Notice:Always re-attach the fuel lines and fuel filter with all original type fasteners and hardware. Do not repair sections of fuel pipes.


Important:Care should be taken not to fold over or twist the fuel pump strainer when installing the fuel sender assembly, as this will restrict fuel flow. Also, assure that the fuel pump strainer does not block full travel of float arm.
Important:Ensure that the fuel sender assembly retaining snap ring is fully seated within the tab slots on the fuel tank.
Position the new fuel sender assembly O-ring on the fuel tank.
Install the fuel sender assembly into the fuel tank.
Install the fuel sender assembly retaining ring while holding the fuel sender assembly down.
Connect the fuel sender electrical connector.
Connect the fuel tank pressure sensor electrical connector.
Connect the quick-connect fittings at the fuel sender assembly. Refer to Plastic Collar Quick Connect Fitting Service .
Install the fuel filler cap.
Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
Inspect for leaks. [align=left]



9.1.
Turn ON the ignition for 2seconds.[/align][align=left]



9.2.
Turn OFF the ignition for 10seconds.[/align][align=left]



9.3.
Turn ON the ignition.[/align][align=left]



9.4.
Inspect for fuel leaks.[/align]



Install the fuel sender access panel.
Notice:Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Install the fuel sender access panel nuts.
Tighten
Tighten the nuts to 10N·m (89lbin).
Install the rear compartment trim panel. Refer to Rear Compartment Trim Panel Replacement in Body Rear End.[/ol][/align]

 

It's easy to do. I replace the fuel pump my son's 2001 Impala in the parking lot ..I replace the sensor on my other son's 2002 Impala at my house..