1. Faulty Fuel Pump: The most common culprit. A failing fuel pump can draw excessive current, blowing the fuse. This often happens as the pump motor starts to wear out or its internal windings short.
2. Wiring Issues:
* Chafed or Damaged Wires: Look for any damage to the wiring harness running to the fuel pump. This is especially important near the tank, where the wires are subject to movement and potential rubbing against metal parts. Rodents can also chew on wiring.
* Corrosion: Corrosion in connectors or at the fuel pump itself can create high resistance, leading to excessive current draw and a blown fuse. Inspect all connectors for corrosion and clean them thoroughly.
* Short to Ground: A wire may be touching the chassis or other grounded metal components. This creates a direct short, drawing a huge amount of current.
3. Fuel Pump Relay: Although less common than a faulty pump or wiring, a bad relay can also cause the problem. The relay controls the power to the fuel pump. A faulty relay can stick closed, drawing excessive current even when the pump isn't needed.
4. Fuel Pump Module (In-Tank): Some Jeep Cherokees have an in-tank fuel pump module. This module contains not only the pump but also other components like the fuel level sender. A short within this module can also blow the fuse.
5. Incorrect Fuse Rating: Though less likely, make sure you're using the correct amperage fuse as specified in your owner's manual. Using a higher amperage fuse is dangerous and won't solve the problem.
Troubleshooting Steps:
1. Check the Fuse: Visually inspect the blown fuse. If it's blown, replace it with a fuse of the correct amperage. Do not simply keep replacing it without investigating the root cause.
2. Inspect the Wiring: Carefully examine the wiring harness running to the fuel pump, looking for any signs of damage, chafing, or corrosion. Pay particular attention to the area near the fuel tank.
3. Test the Fuel Pump Relay (if applicable): Use a multimeter to test the relay's continuity and switching action. Replacing the relay is relatively inexpensive.
4. Check for shorts to ground: Use a multimeter to check for continuity between the fuel pump wires and the chassis. A short will show a low resistance reading.
5. Fuel Pump Test (Advanced): This usually involves disconnecting the fuel pump and testing its resistance (with the pump removed) and current draw to see if it's operating correctly. This requires some electrical knowledge and safety precautions.
6. Check the Fuel Pump Module (If Equipped): Accessing and testing this requires more advanced mechanical skills, and often involves dropping the fuel tank.
Important Safety Note: Working with fuel systems is potentially dangerous due to the flammability of gasoline. Always disconnect the battery's negative terminal before performing any work on the fuel system. Be aware of potential fire hazards. If you're not comfortable performing these checks yourself, take your Jeep to a qualified mechanic.
