1. Verify Power at the Fuel Pump Itself: Don't just check power at the relay. You need to test for power *at the fuel pump's wiring connector*. This requires accessing the pump, usually located in the fuel tank. This is a more involved process and may require dropping the fuel tank (be sure to disconnect the battery before doing this).
* Safety First: Work in a well-ventilated area. Gasoline fumes are explosive. Disconnect the negative battery cable before starting any work near the fuel system.
* Accessing the Pump: Consult your repair manual for the specific procedure for your vehicle. This usually involves dropping the fuel tank.
* Testing for Power: Use a test light or multimeter to check for power at the pump's connector when the ignition is turned on. You should have power at one wire, and ground on the other. If you don't have power, the problem is likely in the wiring between the relay and the pump, or possibly a faulty fuel pump inertia switch (more on this below).
2. Check the Fuel Pump Inertia Switch: This is a safety device that cuts power to the fuel pump in the event of a collision. It's usually found under the dash or in the engine compartment. Look for a small, usually red, button. Push the button to reset it. If the pump starts working, this was the problem.
3. Inspect the Fuel Pump Wiring: Carefully inspect the wiring harness leading to the fuel pump for any signs of damage, such as cuts, chafing, or corrosion. Repair or replace any damaged wiring.
4. Test the Fuel Pump Directly: With the pump disconnected, you can *carefully* test the pump itself by applying 12V directly to the terminals (following the correct polarity, + and -). If the pump doesn't run, the pump itself is likely faulty and needs replacement. Caution: Be extremely careful when applying direct power to the pump.
5. Consider the Fuel Pump Module (if applicable): Some vehicles have an integrated fuel pump module in the tank. This module contains the pump, the sending unit, and the filter. If the problem isn't in the wiring or the pump itself, the module may be at fault.
6. Check the Fuel Pump Pressure (advanced): If you have the tools and expertise, measuring the fuel pressure can help pinpoint the problem. Low pressure indicates a problem with the pump or the fuel filter.
Important Note: Working on the fuel system requires some mechanical aptitude and familiarity with automotive safety procedures. If you're uncomfortable performing these checks, it's best to take your vehicle to a qualified mechanic. Incorrectly handling fuel system components can lead to fire or injury.
