1999 Ford Ranger Fuel Pump Relay Location: The Complete Guide to Finding, Testing, and Replacing It

The fuel pump relay on a 1999 Ford Ranger is located in the power distribution box (fuse box) under the hood, on the driver's side near the fender. It is relay #5, and the corresponding 20-amp mini-fuse for the fuel pump relay and RAP module is fuse #9.

If your 1999 Ford Ranger cranks but won't start, stalls unexpectedly, or you don't hear the fuel pump prime when you turn the key, the fuel pump relay is one of the first components you should check. This guide will walk you through everything you need to know about locating, testing, and replacing the fuel pump relay on your 1999 Ford Ranger.

Understanding the Fuel Pump Relay and Its Role

The fuel pump relay is a small but critical electrical switch that controls power to the fuel pump. When you turn the ignition key to the "ON" position, the relay closes and allows current to flow to the fuel pump, which then pressurizes the fuel system. When the relay fails, the pump cannot receive power, and your engine will not get the fuel it needs to run.

How to Locate the Fuel Pump Relay on a 1999 Ford Ranger

Step 1: Find the Power Distribution Box

The power distribution box is located under the hood of your Ranger. It is mounted on a bracket attached to the driver's side fender apron. Open the hood and look toward the driver's side near the battery. You will see a black plastic box with a cover.

Step 2: Remove the Cover

Press the tabs on the sides of the cover and lift it off. On the underside of the cover, you will find a diagram that shows the location of each relay and fuse. If the diagram is faded or missing, the information below will help you.

Step 3: Identify the Fuel Pump Relay

The fuel pump relay is Relay #5 in the power distribution box. It is usually a small, square, black or gray component that plugs into the fuse box. The relay is often labeled "Fuel Pump" on the diagram or on the relay itself.

Step 4: Locate the Corresponding Fuse

The fuel pump relay is protected by a 20-amp mini-fuse located in position #9 in the same power distribution box. This fuse is labeled "Fuel Pump Relay and RAP Module." Always check this fuse first if you suspect a fuel pump issue, as a blown fuse can mimic relay failure.

Common Symptoms of a Failing Fuel Pump Relay

Recognizing the signs of a failing fuel pump relay can save you time and frustration. Here are the most common symptoms:

1. No-Start Condition
The engine cranks over normally, but it will not start. This is the most common symptom because the fuel pump is not receiving power to deliver fuel to the engine. If you turn the key to the "ON" position and do not hear the fuel pump prime for a few seconds, the relay is likely the culprit.

2. Intermittent Stalling
The engine may start and run fine for a while, then stall suddenly, especially when the engine is warm. This happens because the relay can overheat and fail temporarily, cutting power to the fuel pump. The engine may restart after it cools down, only to stall again later.

3. Difficulty Starting
The engine may take longer than usual to start, requiring you to crank it for an extended period. This is a sign that the relay is not consistently providing power to the pump.

4. Engine Sputtering or Hesitation
You may experience sputtering, hesitation, or loss of power while driving, particularly when accelerating uphill or carrying a heavy load. This is caused by intermittent power delivery to the fuel pump, resulting in inconsistent fuel pressure.

5. No Fuel Pump Priming Sound
When you turn the ignition key to the "ON" position (without starting the engine), you should hear a brief humming sound from the rear of the vehicle as the fuel pump primes. If you hear nothing, the relay may not be activating the pump.

How to Test the Fuel Pump Relay

Before replacing the relay, you can perform a few simple tests to confirm it is faulty.

Method 1: The Relay Swap Test

This is the easiest and quickest diagnostic method.

  1. Locate the fuel pump relay in the power distribution box.
  2. Find another relay in the same box that is identical to the fuel pump relay. Good candidates are the horn relay or the A/C compressor relay.
  3. Swap the two relays. If the engine now starts or the fuel pump primes, the original fuel pump relay was faulty. If the horn or A/C no longer works, this confirms the swap test was successful.
  4. Replace the faulty relay with a new one of the same type.

Method 2: Visual Inspection

Remove the fuel pump relay from the power distribution box and inspect it closely. Look for:

  • Cracks or damage to the plastic housing
  • Corrosion or rust on the metal terminals
  • Burnt or melted areas on the relay

If you see any of these signs, replace the relay immediately.

Method 3: Using a Multimeter

If you have a multimeter, you can test the relay's electrical functionality.

  1. Set your multimeter to the ohms (resistance) setting.
  2. Identify the relay's coil terminals and switch terminals. The pin configuration is usually printed on the relay or available in a wiring diagram.
  3. Apply 12V power to the coil terminals. You should hear a clicking sound as the relay activates.
  4. With power applied, check for continuity across the switch terminals. A functioning relay will show a closed circuit (low resistance). When power is removed, the circuit should be open (high resistance).
  5. If the relay does not click or fails to show continuity, it is defective.

How to Replace the Fuel Pump Relay

Replacing the fuel pump relay is a straightforward task that requires no special tools.

Step 1: Disconnect the Battery
Always disconnect the negative battery terminal before working on any electrical components. This prevents accidental shorts or shocks.

Step 2: Locate and Remove the Old Relay
Open the power distribution box cover and locate relay #5. Grip the relay firmly and pull it straight out. It may require a bit of force, but it should come out without difficulty.

Step 3: Install the New Relay
Insert the new relay into the same socket, ensuring it is oriented correctly. Push it down until it clicks into place securely.

Step 4: Reconnect the Battery and Test
Reconnect the negative battery terminal. Turn the ignition key to the "ON" position and listen for the fuel pump priming sound. If you hear it, the replacement was successful. Start the engine to confirm everything is working properly.

Additional Components to Check

If replacing the relay does not solve the problem, there are two other components you should inspect:

The Fuel Pump Fuse
Fuse #9 is a 20-amp mini-fuse that protects the fuel pump relay circuit. Check this fuse with a multimeter or by visual inspection. If it is blown, replace it with a fuse of the same amperage. If it blows again, there may be a short circuit in the fuel pump wiring.

The Fuel Pump Inertia Switch
The inertia switch is a safety device that cuts power to the fuel pump in the event of a collision. It is located in the right front passenger footwell, near the right front kick panel. If this switch is tripped, the fuel pump will not receive power. Press the reset button on top of the switch to reset it.

Why You Should Consider Replacing Your Fuel Pump with a KEMSO Brand Pump

If your diagnostic process leads you to the conclusion that the fuel pump itself is faulty, rather than just the relay, you need a reliable replacement. The fuel pump is the heart of your fuel system, and installing a high-quality aftermarket pump can restore your vehicle's performance and reliability.

KEMSO Fuel Pumps are designed to be high-performance, direct OEM replacement units. They are engineered to meet or exceed the specifications of your original factory pump. Compared to stock OEM pumps, KEMSO pumps deliver over 20% more flow at 43psi, which ensures your engine gets the fuel it needs for optimal performance. Whether you are using your truck for daily driving, towing, or off-road adventures, a KEMSO pump provides the reliability you need.

Every KEMSO fuel pump comes with a lifetime confidence guarantee, which means you can trust in the quality and durability of the product. KEMSO pumps are individually tested for performance and quality control, ensuring that each unit meets strict standards. The pump kits include everything you need for installation, including fuel strainers, hoses, o-rings, wiring connectors, and clamps. They are compatible with both gasoline and E85/ethanol fuel, making them a versatile choice for any application.

To browse the full selection of KEMSO fuel pumps for your 1999 Ford Ranger and other vehicles, visit their official website: https://www.kemsoracing.com/

Final Thoughts

The fuel pump relay on a 1999 Ford Ranger is a simple component that can cause big problems when it fails. By knowing its location in the power distribution box under the hood (relay #5, fuse #9), you can quickly diagnose and resolve starting and stalling issues. Always start with the easiest checks—swap the relay, inspect the fuse, and check the inertia switch—before moving on to more complex diagnostics. If you determine the fuel pump itself needs replacement, a high-quality aftermarket option like KEMSO provides the performance and reliability you need to keep your Ranger running smoothly for years to come.

For more information on KEMSO fuel pumps and to find the right pump for your vehicle, visit https://www.kemsoracing.com/


Back to blog