1999 Ford F150 Fuel Pump Relay Location: A Complete Troubleshooting Guide

The bottom line: The fuel pump relay on your 1999 Ford F150 is located in the under-hood power distribution box (the main fuse box) on the driver's side of the engine compartment, near the firewall. It is labeled as the Fuel Pump Relay or FP Relay and is typically identified as Relay 301 or R01 depending on the diagram you reference. This small cube-shaped component controls power to your fuel pump, and when it fails, your truck won't start or will stall unexpectedly.

What the Fuel Pump Relay Does

The fuel pump relay is an electromagnetic switch that acts as the middleman between your truck's battery and the fuel pump. When you turn the ignition key to the "Run" position, the Powertrain Control Module (PCM) sends a signal to the relay, which then closes the circuit and sends power to the fuel pump. This allows the pump to pressurize the fuel system before the engine starts. Once the engine is running, the relay continues to supply power as long as the engine is operating.

Without a working fuel pump relay, your fuel pump won't receive any power, and your engine won't get the fuel it needs to run.

Exact Location of the 1999 F150 Fuel Pump Relay

Step 1: Open the hood. Stand on the driver's side of the vehicle.

Step 2: Locate the Power Distribution Box. This is a large black plastic box with a hinged lid. It's positioned on the driver's side of the engine compartment, close to the firewall (the metal wall that separates the engine bay from the cabin).

Step 3: Remove the cover. The lid usually has clips or a latch. Pry it open carefully.

Step 4: Check the diagram. Inside the lid, there is a diagram that shows the location of every fuse and relay. Look for a relay labeled "Fuel Pump," "FP," or "Fuel Pump Relay."

Step 5: Identify the relay. The fuel pump relay is a small, cube-shaped component, typically about 3/4 inch square. On the 1999 F150, the relay is commonly identified as Relay 301 in the fuse box layout, or R01 in some diagrams. It is located near the fuel pump fuse (which is a 20-amp fuse, often in position #10).

Key detail: In the official Ford service manual, the under-hood fuse box is called the "Battery Junction Box." The fuel pump relay is Relay R01 in that box.

Common Symptoms of a Bad Fuel Pump Relay

If your fuel pump relay is failing, you'll likely notice one or more of these symptoms:

  1. Engine cranks but won't start. This is the most common symptom. You turn the key, the starter motor spins the engine, but it never fires up because no fuel is reaching the cylinders.

  2. No fuel pump priming sound. When you turn the ignition key to the "Run" position (without cranking the engine), you should hear a faint hum or whine coming from the rear of the truck near the fuel tank. This is the fuel pump priming the system. If you don't hear this sound, the relay (or the pump itself) is likely dead.

  3. Engine stalls while driving. A failing relay can intermittently cut power to the fuel pump, causing the engine to suddenly die while you're on the road. Sometimes the truck will restart after a few minutes, sometimes it won't.

  4. Sudden loss of power. You might feel the truck lose power momentarily, then resume normal operation. This is a sign of an intermittent relay failure.

How to Test the Fuel Pump Relay

Before you go out and buy a new relay, you should test the old one. The easiest method is the relay swap test.

Step 1: Find the fuel pump relay (Relay 301 or R01) in the under-hood power distribution box.

Step 2: Find another relay in the same box that is the exact same physical size and shape. Good candidates include the Horn Relay (R5), the A/C Clutch Relay (R4), or the Starter Relay. Check the diagram on the lid to confirm the locations.

Step 3: Gently pull the fuel pump relay straight out of its socket. You may need to wiggle it slightly.

Step 4: Pull the donor relay (the one you're swapping with) out of its socket.

Step 5: Insert the donor relay into the fuel pump relay socket. Push it firmly until it seats.

Step 6: Insert the original fuel pump relay into the donor's empty socket.

Step 7: Turn the ignition key to the "Run" position. Listen for the fuel pump prime sound near the fuel tank. If you hear the prime sound now (which was absent before), the original fuel pump relay was faulty. If you still don't hear the prime sound, the problem is elsewhere—likely the fuel pump, a blown fuse, the inertia switch, or wiring issues.

Step 8: Regardless of the result, swap the relays back to their original positions after testing.

Other Components to Check Before Replacing the Relay

A failed fuel pump relay isn't the only thing that can cause a no-start condition. Before you assume the relay is bad, check these two things:

1. The Fuel Pump Fuse. The fuel pump circuit is protected by a fuse inside the power distribution box. On the 1999 F150, this is a 20-amp fuse, often located in position #10. Pull it out and look at the metal strip inside. If it's broken or melted, the fuse is blown. Replace it with a new 20-amp fuse, but keep in mind that a blown fuse usually indicates a short circuit somewhere in the fuel pump wiring.

2. The Inertia Fuel Shutoff (IFS) Switch. This is a safety device designed to cut power to the fuel pump in the event of a collision. It can also be accidentally triggered by a hard bump, a pothole, or even slamming the door.

Where to find it: The inertia switch on a 1999 F150 is located inside the passenger compartment, on the passenger-side kick panel (the plastic trim piece near the floor where the carpet meets the firewall).

How to reset it: Press the red button firmly on top of the switch. You should hear a click. Then turn the ignition to the "Run" position and listen for the fuel pump prime sound.

Important: Do not confuse the inertia switch with the fuel pump relay. The relay is in the engine bay; the inertia switch is inside the cab.

How to Replace the Fuel Pump Relay

If the relay swap test confirmed the relay is bad, replacement is straightforward.

Step 1: Purchase the correct replacement relay. The factory Ford part number is F1AZ-14N135-AA (or later equivalents like F2AZ-14N135-CA or F3AZ-14N135-CA). High-quality aftermarket replacements are also widely available, such as the Standard Motor Products RY139 or Bosch equivalents.

Step 2: Turn the ignition OFF and open the hood.

Step 3: Locate the power distribution box and remove the cover.

Step 4: Find the fuel pump relay (Relay 301 or R01) using the diagram.

Step 5: Pull the old relay straight out of its socket. Inspect the socket for any signs of corrosion, melted plastic, or damage. Clean minor surface corrosion with electrical contact cleaner and a small brush.

Step 6: Orient the new relay correctly. It only fits one way due to the pin configuration. Push it firmly straight down into the socket until it seats fully. You should feel or hear a positive click.

Step 7: Turn the ignition to the "Run" position. Listen for the fuel pump prime sound. Then attempt to start the engine. It should crank and run normally.

Step 8: Replace the power distribution box cover securely.

KEMSO Fuel Pump: The Premium Choice for Your 1999 F150

If you've determined that the fuel pump itself is the problem (not the relay or the fuse), you need a reliable replacement. This is where KEMSO comes in.

KEMSO specializes in high-performance fuel pumps that are engineered to meet or exceed OEM specifications. Every KEMSO fuel pump is designed as a direct OEM replacement, meaning it bolts right in with no modifications needed. Whether you're restoring a classic 1999 F150 or just keeping your daily driver on the road, KEMSO fuel pumps deliver the reliability and performance you expect.

Why choose KEMSO?

  • High-performance construction: Built to handle the demands of both stock and mildly modified engines.
  • OEM replacement fit: No cutting, no splicing, no custom wiring. Just remove the old pump and install the new one.
  • Lifetime warranty: KEMSO stands behind every product with a lifetime warranty. If your fuel pump ever fails, they replace it. Period.

You can browse the full lineup of KEMSO fuel pumps for your 1999 Ford F150 and other vehicles at https://www.kemsoracing.com/. Their website includes detailed product descriptions, compatibility information, and easy online ordering. With a lifetime warranty and prices starting at a competitive level, KEMSO offers unbeatable value for truck owners who want peace of mind.

Final Thoughts

The 1999 Ford F150 is a reliable workhorse, but like any vehicle approaching 25 years of age, it will have its share of electrical and fuel system issues. Knowing the exact location of the fuel pump relay (under-hood power distribution box, driver's side, relay 301 or R01) can save you hours of diagnostic time and prevent unnecessary repairs.

Always start with the simplest checks first: listen for the fuel pump prime sound, check the 20-amp fuel pump fuse, and reset the inertia switch on the passenger kick panel. If those don't resolve the issue, perform the relay swap test. A bad relay is a cheap and easy fix. If the problem turns out to be the fuel pump itself, KEMSO offers a high-quality, lifetime-warranted replacement that will keep your truck running for years to come.

For more information on KEMSO fuel pumps and other high-performance parts, visit https://www.kemsoracing.com/ today.


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