1. Check the Obvious:
* Low Fuel: Sounds simple, but sometimes it's just an empty tank! Try filling the tank and see if the gauge moves.
* Loose Connections: Inspect all electrical connections at the fuel sending unit (in the fuel tank), the fuel gauge itself, and any wiring harness connections along the way. Look for corrosion, loose terminals, or broken wires. Clean any corroded connections with a wire brush and electrical contact cleaner.
* Fuse: Check the fuse associated with the fuel gauge in the fuse box (consult your owner's manual for the location and correct fuse).
2. Troubleshooting the Fuel Sending Unit:
The fuel sending unit is the most common culprit. It's located inside the fuel tank and measures the fuel level. This usually means dropping the fuel tank (a significant undertaking).
* Resistance Test: This requires a multimeter. With the key off, disconnect the wiring harness connector from the fuel sending unit. The connector should have two wires. Consult a wiring diagram or a repair manual (Haynes or Chilton are good options) for the correct wiring. You'll need to find the resistance specifications for the sending unit at different fuel levels (full, half, empty). Compare your measurements to the specifications; significant deviation indicates a faulty sending unit.
* Visual Inspection (if accessible): If you can access the sending unit without dropping the tank (some Explorers allow access from the bed), visually inspect it for damage.
3. Check the Fuel Gauge Cluster:
While less likely than a faulty sending unit, the fuel gauge itself can malfunction. This is harder to diagnose without specialized equipment.
* Gauge Cluster Test: A professional mechanic can test the gauge cluster to see if it's receiving the correct signal from the sending unit.
4. Wiring Issues:
* Wiring Harness: Check the wiring harness between the sending unit and the gauge cluster for any breaks, shorts, or damage. This often involves tracing the wiring along its path.
5. Ground Issues:
* Poor Ground Connection: A poor ground connection can affect the gauge's readings. Inspect the ground connections related to the fuel system and ensure they are clean and tight.
Repair Options:
* Replace the Fuel Sending Unit: This is often the solution if the troubleshooting steps point to a problem with the sending unit. This is usually a significant job requiring fuel tank removal.
* Repair the Wiring: Repair or replace any damaged or corroded wiring.
* Replace the Fuel Gauge Cluster: This is a last resort and typically more expensive than replacing the sending unit.
Important Considerations:
* Safety: Working with fuel systems requires caution. Always disconnect the battery's negative terminal before working on any electrical components related to the fuel system. Ensure proper ventilation when working near fuel.
* Repair Manual: Investing in a repair manual specific to your 1993 Ford Explorer is highly recommended. It provides detailed diagrams, specifications, and repair procedures.
If you're not comfortable performing these repairs yourself, take your Explorer to a qualified mechanic. Replacing the fuel sending unit, in particular, is a complex job. They have the tools and expertise to diagnose the issue accurately and perform the repair safely.
