Here's a general outline. Specific steps might vary slightly depending on your truck's configuration (cab style, bed length, etc.). Always consult a repair manual specific to your year and model F-150 for detailed instructions and diagrams.
Tools and Materials You'll Need:
* Repair Manual: Essential for specific instructions and torque specs.
* Socket Set: Various sizes, including metric and possibly SAE.
* Wrench Set: Again, metric and SAE might be needed.
* Screwdrivers: Phillips and flathead.
* Fuel Pump Pliers (or similar): To disconnect fuel lines.
* New Fuel Sending Unit: Ensure you get the correct part number for your truck.
* Fuel Line Disconnect Tool: Highly recommended for easier and safer fuel line disconnection.
* Safety Glasses: Protect your eyes from fuel splashes.
* Gloves: Protect your hands from fuel and dirt.
* Shop Rags: To clean up spills.
* Jack and Jack Stands: To safely lift and support the truck.
* Wheel Chocks: For added safety.
* Container to catch fuel: A clean container large enough to hold the fuel in the tank.
* Torque Wrench: For tightening bolts to the correct specifications.
Steps (General Outline):
1. Safety First: Disconnect the negative battery terminal. This prevents accidental sparks.
2. Prepare the Truck: Park on a level surface, engage the parking brake, and use wheel chocks. Raise the rear of the truck using a jack and securely support it with jack stands.
3. Access the Fuel Tank: This usually involves removing the bed access panel. The location varies slightly depending on the model. Your repair manual will show the exact location.
4. Disconnect Fuel Lines: Carefully disconnect the fuel lines leading to and from the tank. Use fuel line disconnect tools to avoid damaging the lines or causing leaks. Have rags ready to soak up any fuel that might spill. It's best to relieve pressure in the fuel system before disconnecting the lines. Consult your manual for the proper method.
5. Disconnect Electrical Connections: Disconnect the electrical connector from the fuel sending unit.
6. Remove the Fuel Sending Unit: This usually involves removing several bolts or nuts securing the unit to the fuel tank. Be careful not to drop anything into the fuel tank.
7. Install the New Fuel Sending Unit: Carefully install the new fuel sending unit, ensuring it's properly seated and aligned. Tighten the bolts to the manufacturer's specifications (found in your repair manual).
8. Reconnect Everything: Reconnect the electrical connector, fuel lines, and any other components you disconnected.
9. Lower the Truck: Carefully lower the truck from the jack stands.
10. Test: Reconnect the negative battery terminal and test the fuel gauge to ensure it's working correctly.
11. Top Off the Fuel Tank: Replace the gas cap and add fuel to the tank.
Important Considerations:
* Fuel Vapor: Fuel vapors are explosive. Work in a well-ventilated area.
* Fuel Spills: Clean up any fuel spills immediately to avoid fire hazards.
* Static Electricity: Static electricity can ignite fuel vapors. Ground yourself before working on the fuel system.
* Professional Help: If you're not comfortable performing this repair yourself, take your truck to a qualified mechanic.
This is a general guide. Consult your repair manual for detailed instructions specific to your 1999 Ford F-150. Improperly performing this repair could lead to serious injury or damage to your vehicle. If unsure about any step, seek professional assistance.
