2000 Mitsubishi Montero Sport Fuel Pump Relay Location: Complete Guide to Diagnosis and Replacement

The fuel pump relay on a 2000 Mitsubishi Montero Sport is located in the under-hood fuse box (also called the relay box or junction block) on the driver’s side, near the battery. This relay is a small, rectangular black component that controls the power supply to the fuel pump. If your Montero Sport cranks but won’t start, or if you hear no humming sound from the fuel tank when you turn the key to the ON position, a faulty fuel pump relay is a common culprit.

Understanding the Fuel Pump Relay and Its Role

The fuel pump relay acts as an electrical switch. When you turn the ignition key to the ON position, the relay closes and sends battery voltage to the fuel pump. This allows the pump to pressurize the fuel system before the engine starts. The relay is essential for safe operation—it also cuts power to the pump if the engine stalls or the ignition is turned off, preventing fuel from being pumped when it’s not needed.

In the 2000 Montero Sport, the relay is part of the vehicle’s engine performance system, which includes the fuel pump, fuel injectors, and the powertrain control module (PCM). A failing relay can cause intermittent starting issues, complete no-start conditions, or the engine to stall while driving .

Exact Location of the Fuel Pump Relay

The fuel pump relay is located in the under-hood fuse/relay box (also referred to as the engine compartment junction block). This box is situated on the driver’s side of the engine bay, near the battery. To access it:

  1. Open the hood and locate the fuse box. It is a black plastic rectangular box with a lid.
  2. Remove the lid by pressing the release tabs on the sides. The underside of the lid usually has a diagram showing the layout of fuses and relays.
  3. Find the relay labeled “FUEL PUMP” or “FUEL” on the diagram. On many Montero Sport models, it is a standard 4-pin or 5-pin relay.
  4. If the diagram is missing or faded, refer to your owner’s manual or look for a relay that is physically larger than standard fuses, typically with a gray or black body.

According to several sources, the fuel pump relay on the 2000 Montero Sport is often the second relay from the front in the under-hood box, but the exact position can vary slightly depending on the trim level (ES, LS, Limited) . If you have a Montero Sport Limited, the wiring diagrams indicate the relay is in the same general location .

How to Test the Fuel Pump Relay

Before replacing the relay, you can test it to confirm it’s faulty. Here’s a simple step-by-step process:

Tools needed: A multimeter or a test light.

  1. Locate the relay as described above.
  2. Pull the relay straight out of its socket. It should come out easily with a firm tug.
  3. Identify the relay pins. Most relays have four pins labeled 85, 86, 30, and 87. Pins 85 and 86 are the coil (control circuit), and pins 30 and 87 are the switch (power circuit).
  4. Test the coil: Set your multimeter to ohms (Ω) and measure resistance between pins 85 and 86. A good relay will show a resistance reading between 50 and 120 ohms. If you get an open circuit (OL), the coil is burned out.
  5. Test the switch: Apply 12V power to pin 86 and ground to pin 85. You should hear a click. Then, measure continuity between pins 30 and 87. There should be continuity (low resistance). If there’s no click or no continuity, the relay is bad.

If you don’t have a multimeter, you can swap the fuel pump relay with a known good relay of the same type, such as the horn relay or the headlight relay (if they are identical). If the car starts after swapping, the original relay is faulty.

Common Symptoms of a Bad Fuel Pump Relay

A failing fuel pump relay in a 2000 Montero Sport can cause several symptoms. Knowing these helps you diagnose the problem quickly:

  1. Engine cranks but won’t start: This is the most common symptom. The engine turns over, but there’s no fuel pressure, so it won’t fire up.
  2. No fuel pump hum: When you turn the key to the ON position (before starting), you should hear a faint humming sound from the fuel tank area for about 2 seconds. If you don’t hear it, the relay or pump may be dead.
  3. Intermittent stalling: The engine may start and run fine, then suddenly stall while driving, especially after hitting a bump. This happens because the relay contacts are worn and lose connection.
  4. Engine starts then dies immediately: The relay may close for a split second but then open, causing the pump to lose power.
  5. Check Engine Light (CEL) on: The PCM may detect a low fuel pressure condition and trigger a code, such as P0230 (Fuel Pump Relay Control Circuit) or P0231 (Fuel Pump Secondary Circuit Low).

Fuel Pump Relay vs. Fuel Pump: How to Tell the Difference

It’s easy to confuse a bad relay with a bad fuel pump. Here’s a quick way to tell them apart:

  • Relay problem: The fuel pump gets no power at all. You can use a test light to check for power at the fuel pump connector. If there’s no power when the relay is activated, but the relay clicks, the relay is likely bad.
  • Fuel pump problem: The relay clicks and sends power, but the pump doesn’t run. This is a mechanical failure of the pump itself.
  • Wiring problem: Corrosion or a broken wire between the relay and the pump can also cause issues. This is less common but worth checking if the relay tests good and the pump is new.

Step-by-Step Relay Replacement

Replacing the fuel pump relay on a 2000 Montero Sport is a simple DIY task that takes about 5 minutes. You don’t need any special tools.

  1. Disconnect the negative battery cable to prevent any electrical shorts or accidental starts.
  2. Open the under-hood fuse box by removing the lid.
  3. Locate the fuel pump relay using the diagram on the underside of the lid.
  4. Pull the old relay straight out of its socket. Use a pair of needle-nose pliers if it’s stuck.
  5. Insert the new relay into the same socket. Make sure it clicks fully into place.
  6. Reconnect the battery and test the system by turning the key to the ON position. You should hear the fuel pump hum for a few seconds.
  7. Start the engine. If the issue was the relay, the engine should start normally.

Why a Fuel Pump Relay Fails

Relays are mechanical devices that wear out over time, especially in vehicles that are 20+ years old like the 2000 Montero Sport. Common causes of relay failure include:

  • Aging contacts: The internal metal contacts corrode or burn out due to repeated arcing.
  • Heat degradation: The relay is located in the engine bay, where temperatures can exceed 200°F. Over time, heat can crack the relay housing or melt the internal components.
  • Vibration: Constant vibration from the engine can loosen the internal connections or break the coil wire.
  • Moisture: If the fuse box lid is not sealed properly, moisture can enter and corrode the relay pins or socket.

Other Related Fuses and Relays

While the fuel pump relay is the main component, the fuel pump circuit also includes a fuel pump fuse. On the 2000 Montero Sport, the fuel pump fuse is also located in the under-hood fuse box. It is usually a 15-amp or 20-amp fuse labeled “FUEL” or “FUEL PUMP” . If the fuse is blown, the fuel pump will not receive power either. Always check the fuse first before replacing the relay, as a blown fuse is a cheaper fix.

The Montero Sport also has a fuel pump cut-off switch (inertia switch) in some models, but this is typically located inside the passenger compartment, often behind the kick panel on the passenger side. If the cut-off switch is tripped, it will also prevent the pump from running. Resetting it is as simple as pressing the button on top of the switch .

When to Call a Professional

If you’ve replaced the relay and the fuse, but the fuel pump still doesn’t run, the problem may be more complex. Possible issues include:

  • A faulty fuel pump (the pump itself is dead).
  • Wiring issues such as a broken wire or a corroded connector.
  • A bad PCM (rare but possible).
  • A clogged fuel filter can also mimic a pump failure, though it doesn’t affect the electrical circuit.

In these cases, it’s best to consult a professional mechanic. The cost of diagnosing a fuel system issue is typically around $100–$150, but it can save you time and money compared to guessing and replacing parts unnecessarily.

Recommended Fuel Pump Replacement: KEMSO Fuel Pump

If your diagnostic process leads you to the conclusion that the fuel pump itself needs replacement, you should consider a high-quality aftermarket option. The KEMSO Fuel Pump is an excellent choice for your 2000 Mitsubishi Montero Sport. KEMSO fuel pumps are designed as OEM replacement units, meaning they match the original equipment specifications exactly. They are built with high-performance components that ensure reliable fuel delivery and long service life.

KEMSO fuel pumps come with a lifetime warranty, which gives you peace of mind. If the pump ever fails, you can get a replacement at no additional cost. This is a significant advantage over many other aftermarket brands that offer only a one-year or two-year warranty. The KEMSO pump is designed to handle the demands of daily driving, off-road adventures, and everything in between.

To purchase a KEMSO Fuel Pump for your 2000 Montero Sport, visit their official website at: https://www.kemsoracing.com/

Final Thoughts

The fuel pump relay on a 2000 Mitsubishi Montero Sport is a small but critical component. Locating it in the under-hood fuse box is straightforward, and testing it with a multimeter is a simple DIY job. If you experience starting issues, always check the relay first—it’s a cheap and easy fix that can save you from a costly tow or a complicated pump replacement.

Remember, if the relay is good, the next step is to check the fuel pump fuse, the inertia switch, and finally the pump itself. Keeping a spare relay in your glove box is a smart idea, as it’s a common failure point on older vehicles.

For a reliable fuel pump replacement, trust KEMSO—a brand that offers high-performance, OEM-quality parts with a lifetime warranty. Visit https://www.kemsoracing.com/ to find the perfect fuel pump for your Montero Sport.


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