Here's a general outline. This is not a substitute for a proper repair manual specific to your vehicle. Consult a repair manual (like a Haynes or Chilton manual) for detailed instructions and diagrams specific to your Buick Century. They'll show the exact location of components and provide torque specifications.
1. Preparation and Safety:
* Disconnect the negative battery cable. This is crucial to prevent sparks.
* Ventilate the area. Work in a well-ventilated space, away from any ignition sources. Fuel vapors are highly flammable.
* Gather your tools: This will likely include sockets (various sizes), wrenches, screwdrivers (possibly Phillips and flathead), pliers, a fuel pump removal tool (may be needed depending on design), safety glasses, gloves, rags, a fuel pump disconnect tool, and a new fuel sending unit.
* Have a fire extinguisher readily available.
* Drain some fuel. Lowering the fuel level in the tank will reduce the amount of fuel you'll be working around, significantly decreasing the risk. You can siphon some out using a siphon pump or carefully drain it from the tank. Be careful!
2. Accessing the Fuel Pump/Sending Unit:
* Locate the fuel tank access panel: This is usually located under the rear seat or in the trunk, depending on your model. Consult your repair manual for the exact location.
* Remove the access panel: This may involve removing screws, bolts, or clips.
* Disconnect the fuel lines: Carefully disconnect the fuel supply and return lines. You may need to use fuel line disconnect tools to avoid damaging the lines. Have rags ready to absorb any spilled fuel.
* Disconnect the electrical connectors: Unplug the electrical connectors from the fuel pump and sending unit.
3. Removing the Fuel Pump Assembly (Often includes the sending unit):
* This is the most challenging part. Some models require a specialized tool to remove the fuel pump assembly from the tank. Others may involve carefully removing retaining rings or clips. Your repair manual is essential here.
* Be very careful not to damage the fuel tank or the pump assembly.
4. Replacing the Fuel Sending Unit:
* Once the fuel pump assembly is out, you should be able to access the sending unit itself. This often involves unclipping or unscrewing the unit from the assembly.
* Replace the old sending unit with the new one. Make sure the float arm moves freely.
* Reassemble the fuel pump assembly.
5. Reinstallation:
* Carefully reassemble the fuel pump assembly into the tank.
* Reconnect the electrical connectors.
* Reconnect the fuel lines. Be sure to reconnect the lines correctly!
* Replace the access panel.
* Reconnect the negative battery cable.
6. Testing:
* Check for leaks. Carefully inspect all connections for leaks.
* Start the vehicle. Check the fuel gauge to ensure it's working correctly.
Important Considerations:
* Fuel Pressure: The fuel system may be under pressure even with the negative battery cable disconnected. Be extra cautious.
* Correct Part: Ensure you purchase the correct fuel sending unit for your specific 2003 Buick Century model. The wrong part won't work.
* Professional Help: If you're not comfortable performing this repair yourself, take your vehicle to a qualified mechanic. Working with fuel is dangerous, and improper repair can lead to serious problems.
This is a complex repair. Again, refer to a repair manual for your specific vehicle model. Improperly performing this repair could result in injury or damage to your vehicle. If in doubt, seek professional help.
