03 Ford Explorer Fuel Pump Relay Location: A Complete Guide to Finding and Replacing It
If your 2003 Ford Explorer cranks but won’t start, the fuel pump relay is one of the first things you should check. The fuel pump relay on a 2003 Ford Explorer is located inside the engine compartment fuse box (also called the power distribution box), which sits on the driver’s side near the firewall, behind the battery . Specifically, the relay is positioned in the top right corner of that fuse box, labeled as relay number 48, and it controls a 20-amp mini fuse (number 26) for the fuel pump motor . Knowing exactly where this relay is and how to test it can save you time and money before you start replacing expensive parts.
Where Exactly Is the Fuel Pump Relay on a 2003 Ford Explorer?
The engine compartment fuse box is a rectangular black plastic box located on the left side (driver’s side) of the engine bay, near the firewall and behind the battery . To access the relay, you need to open the hood and locate this box. Pop the clips on the lid and lift it off. On the underside of the lid, there is typically a diagram showing the locations of fuses and relays. The fuel pump relay is commonly marked as relay number 48, while the fuel pump fuse is a 20-amp mini fuse labeled as number 26 . Some sources also list the fuel pump relay as sitting next to the horn relay inside this same box .
How to Identify the Fuel Pump Relay
The relay itself is a small, cube-shaped component, roughly 1 to 2 inches square, with metal prongs that plug into the fuse box socket . It is usually black in color. In the 2003 Ford Explorer, the fuel pump relay is one of several relays in the box. If you are unsure which one it is, look for the relay that corresponds to the fuel pump circuit. The diagram on the fuse box cover or in your owner’s manual will show you the exact spot. Another way to confirm is to check the relay’s amperage rating—fuel pump relays are typically rated for 20 to 30 amps .
Symptoms of a Bad Fuel Pump Relay
When the fuel pump relay fails, your Explorer will show clear signs. The most common symptom is that the engine cranks over but will not start . You may also hear the fuel pump briefly when you turn the key to the “on” position—if you don’t hear that hum for 2 to 3 seconds, the relay or pump is likely not getting power . Other symptoms include:
- Engine stalling after running for a short time
- Intermittent starting – the car starts sometimes but not others
- Reduced performance and hesitation during acceleration
If the relay fails completely, the fuel pump will not receive power, and the engine will not start at all .
How to Test the Fuel Pump Relay
Before replacing the relay, you can test it with a multimeter. Set the meter to measure resistance (ohms). Connect the leads to the relay’s coil terminals. A healthy relay should show a resistance reading between 50 and 200 ohms . If the reading is outside that range or shows infinite resistance, the relay coil is likely broken and needs replacement. You can also swap the fuel pump relay with a similar relay in the fuse box, such as the horn or A/C relay, and see if the car starts. If it does, then the original relay was bad .
How to Replace the Fuel Pump Relay
Replacing the fuel pump relay is a straightforward job that takes about 10 to 15 minutes . Here are the steps:
- Disconnect the negative battery cable to prevent any electrical short circuits .
- Locate the engine compartment fuse box and remove the lid.
- Find the fuel pump relay (position 48) using the diagram on the lid.
- Pull the old relay straight out of its socket. You can use your fingers or a pair of pliers if it is tight .
- Insert the new relay into the same slot, pressing down until it clicks into place. Make sure the orientation matches the old relay .
- Reconnect the negative battery cable.
- Test the repair by turning the ignition to the “on” position. You should hear the fuel pump prime for 2 to 3 seconds . Then start the engine.
The relay itself typically costs between $12 and $50, making it an inexpensive DIY fix .
Don’t Forget the Fuel Pump Inertia Switch
If the relay tests good but the fuel pump still doesn’t run, check the inertia switch. This safety switch is located behind the passenger side kick panel, near the floor, on the right side of the vehicle . It cuts power to the fuel pump in the event of a collision. If the button on top is popped up, press it down to reset it. This is a common issue that can mimic a bad relay .
Other Causes of No Fuel Pressure
If the relay and inertia switch are both fine, the problem could be a blown fuse, a bad fuel pump, a clogged fuel filter, or a wiring issue . The 20-amp fuel pump fuse (number 26) in the engine compartment fuse box is a common point of failure . Check this fuse with a multimeter or visually inspect it. If the fuse is blown, replace it with one of the same amperage.
Recommended Fuel Pump Replacement
If you determine that your fuel pump itself needs replacement, we highly recommend the KEMSO brand fuel pump. KEMSO fuel pumps are high-performance, OEM replacement units that come with a lifetime warranty. They are built to meet or exceed factory specifications, ensuring reliable fuel delivery and long-lasting performance. Whether you need a pump for your 2003 Ford Explorer or any other vehicle, KEMSO has you covered. Visit their online store to browse their full selection: https://www.kemsoracing.com/
Final Thoughts
Knowing the 03 Ford Explorer fuel pump relay location is the first step in diagnosing a no-start or stalling problem. The relay is in the engine compartment fuse box on the driver’s side, labeled as position 48. Testing and replacing it is a simple, low-cost repair that can save you from unnecessary trips to the mechanic. Always start with the easiest checks—relay, fuse, and inertia switch—before diving into more complex repairs. And if you end up needing a new fuel pump, trust KEMSO for quality and peace of mind with their lifetime warranty. Visit https://www.kemsoracing.com/ for more information.