Here's a breakdown of likely causes:
* Blown Fuse: Check the fuse(s) associated with the fuel pump circuit in the fuse box (under the hood and/or inside the car). The owner's manual will tell you which fuses to check. A blown fuse is the most common and easiest-to-fix problem.
* Faulty Wiring: There might be a break, short, or corrosion in the wiring between the battery (or a power source controlled by an ignition switch) and the fuel pump relay. Visually inspect the wiring harness leading to the relay for any damage.
* Ignition Switch Problem: The fuel pump relay is usually activated by the ignition switch. A malfunctioning ignition switch might not send power to the relay circuit.
* Power Relay: Many cars utilize other relays in the circuit before power reaches the fuel pump relay. One of those relays could be faulty, preventing power from flowing to the fuel pump relay. (Check the wiring diagrams to identify these).
* Circuit Breaker: Some vehicles use a circuit breaker instead of a fuse. Check to see if there's a relevant circuit breaker that might have tripped.
* Computer (PCM) Problem: While less likely, a problem with the Powertrain Control Module (PCM) could prevent it from sending the signal to activate the relay. This usually requires diagnostic testing.
Troubleshooting Steps:
1. Check the fuse(s): This is the absolute first step. Replace any blown fuse with one of the correct amperage.
2. Visual inspection of wiring: Look for any obvious damage to the wires leading to the relay.
3. Use a test light or multimeter: With the ignition on, probe the power wire going *to* the fuel pump relay. You should have battery voltage. If not, trace the wire back towards the battery or fuse box to find the break.
4. Check other relays: Consult your vehicle's wiring diagram to identify if there are other relays in the circuit.
5. Check for power at the ignition switch: (Advanced troubleshooting) If you suspect the ignition switch, check if power is reaching the switch's output for the fuel pump circuit.
6. Professional diagnosis: If you can't find the problem after checking these steps, consider taking your vehicle to a qualified mechanic for diagnosis using a scan tool.
Remember to disconnect the negative battery terminal before performing any wiring tests to prevent accidental short circuits. Always refer to your vehicle's wiring diagram for precise locations of components and fuse ratings.
