1. Assessing the Problem:
* Identify the exact issue: Is the gauge completely inaccurate, intermittently fluctuating, or reading empty when the tank is full? This helps determine the likely cause (faulty float, bad resistor, corroded connections, etc.).
* Check for obvious problems: Before diving into the tank, inspect the wiring harness for damaged or corroded wires, and ensure the gauge cluster itself is functioning correctly. A faulty gauge could be misinterpreted as a fuel sender issue.
2. Gathering Tools and Materials:
* Safety First: Eye protection, gloves, and a well-ventilated area are essential. Fuel is flammable.
* Tools: Socket wrench set (metric), screwdrivers (Phillips and flathead), pliers, wire crimper, multimeter, possibly a fuel pump removal tool (depending on your design), and a clean container for fuel.
* Parts: You might need a new float arm, resistor, or soldering equipment (depending on the diagnosis). A new gasket is highly recommended.
3. Procedure (General Steps - Specifics vary by year and trim):
* Disconnect the battery: This is crucial to prevent sparks and electrical damage.
* Drain the fuel tank: This is the most important safety precaution. Siphon the gas into approved containers, following all safety guidelines. Never work near open flames.
* Access the fuel pump and sending unit: This usually involves dropping the fuel tank (this is the most labor-intensive part). Consult a repair manual specific to your 1998 Honda Passport for detailed instructions on accessing the tank and fuel pump assembly. This often involves removing the rear seats, dropping the fuel lines and electrical connectors, and possibly unbolting straps holding the tank in place.
* Remove the fuel pump assembly: This assembly typically houses the sending unit. The exact method varies depending on your Passport's setup. Often, a specialized tool is needed to properly remove the fuel pump from the tank.
* Inspect the sending unit: Once removed, carefully inspect the float arm for damage, cracks, or corrosion. Check the resistor for continuity using your multimeter. Examine the wiring for damage or corrosion.
* Repair or replace components: Depending on what's faulty, you may be able to solder a broken connection, replace the float, or replace the entire resistor assembly. This often requires desoldering old components and soldering new ones. This step requires electronics experience and the proper equipment.
* Reassemble: Carefully clean everything before reassembling. Use a new gasket to prevent leaks.
* Reconnect: Attach all fuel lines, wiring, and ground connections securely.
* Refill the fuel tank: Refill the tank slowly to avoid any leaks.
* Reconnect the battery: Check the fuel gauge.
Important Considerations:
* Repair Manual: A repair manual specific to your 1998 Honda Passport is absolutely essential. It will provide detailed diagrams and instructions, saving you time and preventing mistakes.
* Safety: Fuel is extremely flammable. Take all necessary safety precautions.
* Complexity: Replacing the entire fuel sending unit is usually much easier and quicker than attempting a repair, especially if you lack experience with automotive electrical systems and soldering. The cost difference might be minimal, making replacement the better option.
Recommendation: Unless you have experience repairing fuel sending units and have access to the correct tools and information (repair manual), consider replacing the entire fuel sending unit as the most straightforward solution. It's a much safer and likely more cost-effective approach for most DIYers. A professional mechanic can also do this quickly and safely.
