* Failing Fuel Pump: While it *could* be the pump itself drawing excessive current (due to internal shorting or binding), this is less likely if the fuse only blows after driving for some time. A completely failed pump would usually blow the fuse immediately upon trying to start.
* Fuel Pump Relay: The relay switches power to the pump. A failing relay can cause intermittent power surges or failures, leading to a blown fuse after the pump has been running for a while and things heat up.
* Wiring Harness Issues: Look for chafing, corrosion, or damage to the wiring between the fuel pump, relay, and fuse. Heat from the engine compartment can exacerbate existing problems. A short circuit in the wiring is a prime suspect.
* Fuel Pump Inertia Switch: Some cars have an inertia switch that cuts power to the fuel pump in a collision to prevent fires. It's possible this switch is malfunctioning and intermittently cutting and restoring power, leading to surges that blow the fuse. This is often found under the dash or in the engine bay.
* Fuel Level Sensor: While less common, a faulty fuel level sensor *could* in some cases draw extra current or cause erratic behavior leading to fuse failure.
* Overheating Components: The fuel pump and its related components (relay, wiring) are subject to engine heat. If any component is close to failing, the added heat from extended driving might push it over the edge, causing an overload and blowing the fuse.
Troubleshooting Steps:
1. Check the Fuse: Make sure you're using the correct replacement fuse (amperage rating). If the new fuse blows immediately, the problem is likely in the wiring or the pump itself (or its relay). If it blows after driving, the problem is more intermittent.
2. Inspect the Wiring: Carefully examine the entire wiring harness leading to the fuel pump, paying close attention to areas near the engine and exhaust manifold. Look for any signs of damage, chafing, or corrosion. Repair or replace any damaged wiring.
3. Test the Fuel Pump Relay: Replace the relay with a known good one. You can often swap it with a similar relay (check your owner's manual or online forums for possible substitutes). This is a relatively inexpensive and easy test.
4. Locate and Check the Inertia Switch: If your Cougar has one, find its location, reset it (usually a button), and check for any damage.
5. Check the Fuel Pump (Advanced): This requires more advanced tools and potentially removing the fuel pump. A fuel pressure test will reveal if the pump is delivering adequate pressure. However, given the intermittent nature of the problem, this is lower on the priority list unless other steps fail.
Important Safety Note: Working with the fuel system involves flammable materials. Always disconnect the battery's negative terminal before starting any work. Be mindful of potential fire hazards. If you're not comfortable performing these checks yourself, take your Cougar to a qualified mechanic.
