Bronco Fuel Pump Relay Location: A Complete Guide for Ford Bronco Owners

If your Ford Bronco cranks but won't start, or if it stalls unexpectedly while driving, the fuel pump relay is often the first component to check. The fuel pump relay on most Ford Broncos is located in the engine compartment, inside the power distribution box (also called the fuse box) mounted near the driver's side fender well or firewall. This small electrical component controls the power supply to your fuel pump, and when it fails, your engine won't get the fuel it needs to run. Understanding exactly where to find this relay and how to test it can save you time and money on unnecessary repairs.

Where Is the Fuel Pump Relay on Different Ford Bronco Models?

The location of the fuel pump relay varies slightly depending on the year and model of your Bronco. Here is a breakdown by model year:

1990 Ford Bronco (Full-Size)
The fuel pump relay is located in the under-hood fuse box on the driver's side of the engine compartment. It is often labeled as "FPR" or "Fuel Pump Relay" on the fuse box diagram. To access it, open the fuse box cover and look for the diagram on the inside of the lid. The relay is a standard 5-pin relay that pulls straight out of its socket.

1988-1990 Ford Bronco II
The fuel pump relay on the Bronco II is typically mounted on the right side (passenger side) fender well in the engine compartment, behind the air box. On the 1988 Bronco II, it is located in the under-hood fuse box, often labeled as "Fuel Pump" or "FP". For the 1990 Bronco II, one owner reported finding it next to the main fuse box under the hood on the right fender well, attached with a single screw, and it has "Bosch" and "12V 30A" stamped on it.

1994 Ford Bronco
The fuel pump relay is located in the engine compartment's relay box, which is mounted near the driver's side fender. You may need to consult the owner's manual or a service manual for the exact location within the relay box, as it may vary slightly based on the specific model and engine configuration.

1995 Ford Bronco
The fuel pump relay is found in the Power Distribution Box (fuse box) under the hood. This box is typically located on the driver's side of the engine compartment, near the firewall. It is a black plastic box with a removable lid. The relay is often a mini-relay, and you should consult the diagram on the inside of the lid for the exact labeling.

1996 Ford Bronco
The fuel pump relay is located in the engine compartment, inside the power distribution box (PDB). This box is a black plastic box filled with fuses and relays.

1997 Ford Bronco
The fuel pump relay is located in the engine compartment fuse box. It is labeled as Relay R4 for the fuel pump on gasoline models.

How to Identify the Fuel Pump Relay

Once you have opened the power distribution box, you need to identify which relay is the fuel pump relay. Here is how:

  1. Check the diagram on the fuse box lid. Most Ford Broncos have a diagram printed on the inside of the power distribution box cover that shows the location and function of each fuse and relay. Look for a relay labeled "Fuel Pump," "Fuel Pump Relay," "FPR," or "FP."

  2. Look for a specific relay designation. On the 1997 Bronco, for example, the fuel pump relay is designated as Relay R4. On other models, it may be labeled with a specific number or letter code.

  3. Note the relay type. The fuel pump relay is typically a standard 4-pin or 5-pin relay. On the 1990 Bronco, it is a 5-pin relay. On the 1988 Bronco II, it is a standard 4-pin or 5-pin relay.

  4. Follow the wiring. If you are having trouble identifying the relay, you can try tracing the wiring from the fuel pump. The wires leading to the fuel pump relay should be connected to the fuel pump circuit.

How to Remove the Fuel Pump Relay

Removing the fuel pump relay is a straightforward process. Follow these steps:

  1. Ensure the vehicle is turned off and the ignition is in the Off position to prevent accidental activation of the fuel pump.

  2. Locate the fuse/relay box under the hood and open its cover.

  3. Identify the fuel pump relay by comparing it to the diagram on the fuse box lid or consulting the owner's manual.

  4. Pull the relay straight out of its socket. If it is stubborn, gently rock it side to side while pulling. You can use a flathead screwdriver or a relay puller tool to gently pry the relay out.

  5. Inspect the relay for any signs of damage, such as cracks, melted plastic, or corrosion. If the relay looks damaged, replace it immediately.

Symptoms of a Failing Fuel Pump Relay

Knowing the symptoms of a failing fuel pump relay can save you time when diagnosing fuel-related issues. Here are common signs to watch out for:

  1. Engine won't start. This is one of the most obvious symptoms. If the fuel pump relay is faulty, it may not be sending power to the fuel pump, preventing it from delivering fuel to the engine. The engine may crank, but it will not start.

  2. Engine stalling. A failing fuel pump relay can cause the engine to stall intermittently, especially when the engine is under load or when driving at higher speeds.

  3. No fuel pump priming sound. When you turn the ignition key to the "on" position (but don't crank the engine), you should hear a brief whirring sound from the fuel pump as it primes. If you do not hear this sound, the relay could be the culprit.

  4. Rough idling or misfiring. A failing relay might deliver inconsistent power to the fuel pump, causing the fuel supply to fluctuate. This can make the engine idle poorly or run roughly.

How to Diagnose a Faulty Fuel Pump Relay

Before replacing the relay, it is a good idea to diagnose whether it is actually the problem. Here is a simple step-by-step process:

  1. Listen for the fuel pump. Turn the ignition key to the "on" position and listen for a brief whirring sound from the fuel pump. If you do not hear it, the relay may be faulty.

  2. Check the fuel pump fuse. The fuel pump has its own fuse, which is usually located in the power distribution box along with the relay. Check the fuse first. If the fuse is blown, replace it with a fuse of the same amperage rating.

  3. Swap relays. Relays are often the same type and size, so you can perform a quick test by swapping the fuel pump relay with another relay that does the same job, such as the horn relay or the air conditioning clutch relay. If your Bronco starts after the swap, the original fuel pump relay is likely bad.

  4. Test the relay with a multimeter. Remove the relay from the PDB and use a multimeter to check the continuity between the terminals. This test confirms that the internal switch of the relay is working correctly.

Common Causes of Fuel Pump Relay Failure

Understanding why fuel pump relays fail can help you prevent future issues. The most common causes include:

  • Current overload. If the fuel pump or the electrical system is drawing more current than the relay is designed to handle, the relay contacts can overheat and burn out.

  • Short circuit. A short circuit in the electrical system can cause a current overload through the relay, which can burn the contacts or damage the relay's coil.

  • Defective internal components. Over time, the internal components of the relay, such as the electromagnetic coil or mechanical contacts, can wear out or fail due to repeated use, vibrations, or simply the age of the component.

Other Causes of Fuel Pump Failure

If the relay is functioning correctly, other possible causes of fuel pump failure include:

  • Blown fuse. The fuse protecting the fuel pump relay, or the fuel pump fuse itself, may be blown.

  • Impact sensor activation. Some vehicles are equipped with an impact sensor, also known as an inertia switch, that cuts off power to the fuel pump in case of an accident. If this sensor is activated, the pump will stop operating.

  • Engine control unit (ECU) issues. The ECU manages various vehicle functions, including the operation of the fuel pump. A failure in the ECU or in the sensors that send data to it can affect the pump's operation.

  • Clogged fuel filter. A very dirty or blocked filter can reduce fuel flow, causing the pump to work harder, which can lead to its failure.

  • Wiring problems. Damaged, corroded, or loose wires can prevent the pump from receiving the necessary power to operate.

  • Defective fuel pump. The pump itself may be failing due to wear, internal damage to its components, or manufacturing defects.

Upgrade Your Fuel System with KEMSO Fuel Pumps

If you need to replace your fuel pump, consider upgrading to a high-quality aftermarket option. KEMSO fuel pumps are designed as direct replacements for stock OEM pumps, built to match or exceed the original specifications. They deliver over 20% more flow at 43 psi compared to the stock pump, which can improve engine performance and throttle response. KEMSO fuel pumps are compatible with both gasoline and ethanol-blended fuels like E85, and each pump is individually tested for flow and performance before leaving the factory. Best of all, KEMSO offers a lifetime warranty on all their fuel pumps, giving you peace of mind for as long as you own your vehicle. Whether you drive a car, truck, motorcycle, ATV, or personal watercraft, KEMSO has the right fuel pump for your application. Visit KEMSO Racing today at https://www.kemsoracing.com/ to browse their full selection and find the perfect pump for your Bronco.


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