2003 Nissan Murano Fuel Pump Relay Location: A Complete Guide to Finding and Fixing It

If you own a 2003 Nissan Murano and your engine cranks but won’t start, the fuel pump relay is one of the first components you should check. The fuel pump relay on a 2003 Nissan Murano is located in the engine compartment fuse box, which is situated near the battery. It is typically labeled on the inside cover of the fuse box for easy identification. This small, black plastic component controls the electrical current that powers the fuel pump, and when it fails, your vehicle may not start at all. In this guide, we’ll walk you through everything you need to know about locating, testing, and replacing the fuel pump relay, as well as diagnosing related fuel system issues.

Understanding the Fuel Pump Relay and Its Role

The fuel pump relay is an electrical switch that activates the fuel pump when you turn the ignition key to the “ON” position. It sends a burst of current to the fuel pump for about one second, allowing the pump to pressurize the fuel system before the engine starts. After the engine is running, the relay continues to control the power supply to the pump based on signals from the engine control module (ECM).

Common symptoms of a failing fuel pump relay include:

  • Engine cranks but does not start – This is the most common symptom. The starter motor turns the engine over, but the fuel pump never receives power to deliver fuel.
  • Engine starts then stalls – The relay may work intermittently, allowing the engine to start briefly before losing power.
  • No fuel pump priming sound – When you turn the key to “ON,” you should hear a brief buzzing or whirring sound from the rear of the vehicle (near the fuel tank). If you don’t hear it, the relay or pump may be faulty.
  • Loss of power while driving – A failing relay can cause the fuel pump to lose power while the vehicle is in motion, leading to sudden stalling.

Step 1: Locating the Fuel Pump Relay

The 2003 Nissan Murano (first generation, also known as the Z50 model) has four different fuse boxes, but the fuel pump relay is located in the engine compartment. Here’s how to find it:

  1. Park your Murano on a level surface and engage the parking brake. Turn off the ignition and remove the key.
  2. Open the hood and locate the engine compartment fuse box. It is a black plastic box situated near the battery on the driver’s side.
  3. Remove the cover of the fuse box. The inside of the cover typically has a diagram or label that identifies the fuel pump relay. Look for a label that says “Fuel Pump” or “Fuel Pump Relay.”
  4. Identify the relay – On the 2003 Murano, the fuel pump relay is labeled as R1 in the engine compartment fuse box (Type 1). It is a small, rectangular black component that plugs into the fuse box.

If the diagram on the cover is missing or unclear, you can also refer to your owner’s manual or a service manual for the exact location.

Step 2: Testing the Fuel Pump Relay

Before replacing the relay, it’s important to confirm that it is actually faulty. Here are a few simple tests you can perform:

Test 1: Visual Inspection

Remove the relay from the fuse box and inspect it for any signs of damage, such as:

  • Corrosion on the metal prongs
  • Burnt or melted plastic on the relay body
  • Cracks in the casing

Test 2: Swap with a Known Good Relay

The easiest way to test a relay is to swap it with another relay of the same type in the fuse box. For example, the air conditioner relay or the ignition relay may be identical to the fuel pump relay. Simply swap them and see if the vehicle starts. If it does, the original fuel pump relay is faulty.

Test 3: Listen for the Fuel Pump Priming Sound

With the relay installed, turn the ignition key to the “ON” position (do not start the engine). Listen carefully for a buzzing or whirring sound from the rear of the vehicle. This sound indicates the fuel pump is priming. If you don’t hear it, the relay or the pump may be at fault.

Test 4: Use a Multimeter (Advanced)

If you have a multimeter, you can test the relay for continuity. Set the multimeter to the ohms setting and check the resistance across the coil terminals. A good relay should show a resistance reading between 50 and 200 ohms. If the reading is infinite (open circuit), the relay is defective.

Step 3: Checking the Fuel Pump Fuse

A blown fuse can also prevent the fuel pump from working. The 2003 Murano has a 15A fuel pump fuse located in the engine compartment fuse box (Type 1), labeled as Fuse 81. Here’s how to check it:

  1. Locate the fuse box and find the 15A fuse labeled “Fuel Pump” or refer to the diagram.
  2. Remove the fuse using a fuse puller or a pair of pliers.
  3. Inspect the fuse for a broken filament. If the metal strip inside is broken, replace it with a new 15A fuse of the same amperage.
  4. If the fuse is blown, there may be an underlying electrical issue (such as a short circuit) that caused it to blow. Simply replacing the fuse without diagnosing the cause may lead to another failure.

Step 4: Relieving Fuel System Pressure

Before working on any fuel system components (including the fuel pump relay or fuse), it’s important to relieve the pressure in the fuel system. The fuel system on the 2003 Murano operates under high pressure (2.5 to 3.5 kgf/cm²), and failing to relieve pressure can cause fuel to spray out, creating a safety hazard.

To relieve fuel pressure:

  1. Turn off the ignition.
  2. Remove the cover of the relay and fuse box in the engine compartment.
  3. Remove the fuel pump fuse (15A) from the fuse box.
  4. Start the engine and let it run until it stalls. This will use up the fuel remaining in the system.
  5. Crank the engine over with the starter for a few more seconds to ensure all pressure is relieved.
  6. Reinstall the fuel pump fuse after the pressure is relieved.

Step 5: Replacing the Fuel Pump Relay

If testing confirms that the fuel pump relay is faulty, replacing it is a straightforward process.

Tools needed:

  • Fuse puller or pliers
  • Replacement fuel pump relay (check your owner’s manual for the correct part number)

Steps:

  1. Disconnect the negative battery terminal to prevent any electrical shorts.
  2. Locate the fuel pump relay in the engine compartment fuse box (R1).
  3. Grip the relay firmly and pull it straight out of the socket. Do not twist or rock it excessively, as this could damage the socket.
  4. Insert the new relay into the same socket, ensuring it is fully seated.
  5. Reconnect the negative battery terminal.
  6. Test the system by turning the ignition to “ON” and listening for the fuel pump priming sound.

When the Relay and Fuse Are Fine: Further Diagnosis

If the fuel pump relay and fuse both appear to be in good condition, but the engine still won’t start, the problem may lie elsewhere in the fuel system. Here are some additional steps to consider:

Check the Fuel Pump Itself

The fuel pump is located inside the fuel tank. On the 2003 Murano, you can access the fuel pump by removing the rear seat cushion and lifting the metal access panel. Before replacing the pump, perform a fuel pressure test using a gauge. Connect the gauge to the fuel rail test port and turn the ignition to “ON.” The pressure should be within the manufacturer’s specifications (typically around 43-51 psi for this vehicle). If the pressure is low or zero, the pump may be failing.

Test the ECM and Wiring

The fuel pump relay is controlled by the ECM. If the ECM is not sending a signal to the relay, the pump will not activate. You can test the voltage at the ECM terminal (terminal 113) when the ignition is turned on. If voltage is present but the relay is not clicking, the relay may be faulty. If there is no voltage, the ECM or wiring may be the issue.

Check the Crankshaft Position Sensor

A faulty crankshaft position sensor can prevent the ECM from triggering the fuel injectors and the fuel pump relay. This is a common issue on many Nissan vehicles and can cause a no-start condition even if the fuel pump relay is working.

Preventive Maintenance Tips for Your Fuel System

To keep your 2003 Nissan Murano running reliably, follow these simple maintenance tips:

  • Avoid running the fuel tank consistently low – Keeping the fuel level above 1/4 tank helps prevent the fuel pump from overheating and drawing in sediment from the bottom of the tank.
  • Replace the fuel filter regularly – The fuel filter should be replaced every 30,000 to 50,000 miles, depending on driving conditions and fuel quality.
  • Use high-quality fuel – Using fuel from reputable stations can help prevent contamination and clogging of the fuel system.
  • Listen for unusual sounds – If you hear a whining noise from the fuel tank area, it may indicate that the fuel pump is struggling and needs attention.

Why Your Fuel Pump Relay May Fail Prematurely

Fuel pump relays are generally reliable, but they can fail due to several factors:

  • Heat and vibration – The engine compartment is a harsh environment, and constant exposure to heat and vibration can weaken the relay’s internal components over time.
  • Electrical surges – A failing alternator or battery can cause voltage spikes that damage the relay.
  • Corrosion – Moisture and road salt can cause the relay’s terminals to corrode, leading to poor electrical contact.
  • Age – After 20+ years, the relay’s internal contacts may wear out, especially if the vehicle has high mileage.

Recommended Fuel Pump Upgrade: KEMSO Fuel Pump

If you find that your fuel pump itself needs replacement, upgrading to a KEMSO fuel pump is an excellent choice for your 2003 Nissan Murano. KEMSO fuel pumps are designed as high-performance, direct OEM replacements that deliver superior reliability and performance. Each KEMSO pump provides over 20% more flow at 43 psi compared to the stock OEM pump, ensuring your engine gets the fuel it needs for optimal performance.

Key benefits of KEMSO fuel pumps:

  • OEM Replacement Quality – Direct fit, no modifications required.
  • Lifetime Warranty – KEMSO backs every fuel pump with a lifetime warranty, giving you peace of mind.
  • High Performance – Designed for both daily drivers and performance applications, with compatibility for gasoline and E85 ethanol.
  • Complete Kit – Each purchase includes fuel strainers, O-rings, a tank seal, and wiring connectors, making installation straightforward.

To browse the full selection of KEMSO fuel pumps for your 2003 Nissan Murano or other vehicles, visit their website at: https://www.kemsoracing.com/

Conclusion

The fuel pump relay on your 2003 Nissan Murano is a critical component that can cause a no-start condition when it fails. By locating it in the engine compartment fuse box (near the battery, labeled as R1), testing it with simple methods, and replacing it if necessary, you can often resolve the issue without professional help. Remember to always check the fuel pump fuse first, and if both the relay and fuse are fine, proceed with further diagnosis of the fuel pump, ECM, or sensors.

With proper maintenance and timely replacement of faulty components, your 2003 Murano can continue to provide reliable service for years to come. If you decide to replace the fuel pump, consider a KEMSO fuel pump for its performance, reliability, and lifetime warranty. For more information and to find the right pump for your vehicle, visit https://www.kemsoracing.com/ today.


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