1. Relay: The fuel pump relay is the most likely culprit. Even if the fuse is good, the relay itself might be faulty. Locate the fuel pump relay (your owner's manual or a reliable online resource for your car's year and model will tell you where it is, often in the underhood fuse box). Try swapping it with a known good relay of the same type (if you have one available). If the pump runs with the swapped relay, you've found the problem.
2. Relay Wiring: If swapping the relay doesn't fix it, inspect the wiring going to and from the fuel pump relay. Look for:
* Broken wires: Carefully check for any breaks, chafing, or corrosion in the wires. Pay special attention to areas where wires might rub against metal parts.
* Loose connections: Ensure all connectors at the relay and the related components are securely connected.
* Corrosion: Clean any corrosion you find on the connectors with a wire brush or contact cleaner.
3. Inertia Switch: Some vehicles have an inertia switch that cuts power to the fuel pump in case of a collision. This is a safety feature. Locate the inertia switch (again, consult your manual) and check if it's tripped. It usually has a button that you can press to reset it.
4. Fuel Pump Inertia Switch: Some cars have an additional inertia switch specifically for the fuel pump. Check your car's documentation to verify if it has one.
5. Computer/ECU: It's less likely, but a problem with the car's computer (Engine Control Unit or ECU) could prevent the fuel pump from receiving the signal to turn on. This is more difficult to diagnose and often requires a diagnostic scan tool to check for trouble codes.
6. Wiring Harness: A problem within the main wiring harness could also be the cause. This is a more involved diagnosis that may require tracing the wiring from the ECU to the fuel pump.
Important Safety Precautions:
* Disconnect the negative battery terminal before working on any electrical components in your car.
* Work in a well-ventilated area when dealing with fuel systems. Gasoline fumes are flammable and potentially explosive.
* Use caution when working near the fuel pump as it contains pressurized fuel.
If you're not comfortable working with car electrical systems, it's best to take your car to a qualified mechanic for diagnosis and repair. Improperly handling electrical systems can lead to further damage or even injury.
