Here's a general outline. Always consult a repair manual specific to your 1989 Grand Wagoneer for detailed instructions and diagrams. These instructions are for informational purposes only and may not be completely accurate for your specific vehicle.
1. Safety Precautions:
* Disconnect the negative battery terminal. This prevents sparks that could ignite fuel vapors.
* Work in a well-ventilated area. Fuel fumes are extremely flammable and dangerous.
* Wear safety glasses and gloves.
* Have a fire extinguisher readily available.
* Use a fuel-safe container to collect any spilled fuel.
2. Preparation:
* Locate the fuel tank. It's usually under the vehicle, near the rear axle.
* Gather your tools: Sockets (various sizes), wrenches (various sizes), screwdrivers (Phillips and flathead), pliers, a fuel pump disconnect tool (highly recommended), safety glasses, gloves, rags, fuel-safe container, new fuel sending unit, and possibly a new fuel filter. A shop manual is essential.
* Drain the fuel tank partially. This reduces the amount of fuel you'll be working around and makes the tank lighter. You can siphon the fuel out using a siphon pump and appropriate hose. Dispose of the fuel properly – do not pour it on the ground.
3. Accessing the Fuel Tank:
* Lower the fuel tank: This usually involves removing the fuel tank straps and lowering the tank enough to access the sending unit. This might require removing the exhaust system or other components depending on your vehicle's configuration. This is the most labor-intensive part of the job. Consult your repair manual for specific steps.
* Support the tank properly while it's lowered to prevent it from dropping and causing damage. Use jack stands or a sturdy support system.
4. Replacing the Fuel Sending Unit:
* Disconnect the fuel lines: Carefully disconnect the fuel lines from the sender unit. Use the fuel pump disconnect tool to avoid damaging the lines or the quick-connect fittings. Plug the lines to prevent fuel leakage.
* Disconnect the electrical connector: Unplug the electrical connector from the sending unit.
* Remove the fuel sending unit: The sending unit is usually held in place with bolts or a retaining ring. Carefully remove the unit.
* Install the new fuel sending unit: Install the new unit, ensuring it's properly seated and aligned.
* Reconnect the electrical connector and fuel lines: Ensure the electrical connections are secure and the fuel lines are properly attached and clamped.
5. Reassembly:
* Raise the fuel tank: Carefully raise the fuel tank back into its original position.
* Secure the fuel tank straps: Tighten the fuel tank straps securely.
* Reconnect the exhaust system or other components: Reinstall any components that were removed to access the tank.
* Reconnect the negative battery terminal.
6. Testing:
* Fill the fuel tank: Fill the fuel tank with fuel.
* Check for leaks: Inspect the fuel lines and connections for any leaks.
* Test the fuel gauge: Start the vehicle and verify that the fuel gauge is working correctly.
Important Considerations:
* This procedure can be significantly more complex than described. Accessibility varies depending on the specific vehicle. The repair manual will provide detailed illustrations and steps that are crucial for success.
* Working with fuel is dangerous. Take all necessary precautions. If you are not comfortable with this type of repair, it's best to have a qualified mechanic perform the work.
This is a general guideline. You absolutely must consult a repair manual specific to your 1989 Jeep Grand Wagoneer before attempting this repair. Improperly performing this repair could lead to damage to your vehicle or serious injury.
