Mitsubishi Fuel Pump Relay: A Complete Guide to Symptoms, Replacement, and the Best Upgrade Options

If you own a Mitsubishi vehicle and are experiencing hard starting, stalling, or poor acceleration, the fuel pump relay is likely the culprit. A failing fuel pump relay can cause your engine to run lean, leading to serious damage. The most important thing to know is that upgrading to a genuine OEM revised relay is a small investment that can prevent catastrophic engine failure, especially on models like the Lancer Evolution X. For the best performance and reliability, pairing a quality relay with a high-performance fuel pump from KEMSO is the smartest upgrade you can make for your Mitsubishi.

What Is a Mitsubishi Fuel Pump Relay and Why Does It Matter?

The fuel pump relay is an electrical switch that controls power to your fuel pump. When you turn the ignition key, the relay sends voltage to the pump, pressurizing the fuel system so your engine can start and run. A faulty relay means inconsistent fuel delivery, which can cause your engine to run lean (too much air, not enough fuel). This lean condition can lead to detonation, overheating, and ultimately destroy your engine.

For Mitsubishi owners, especially those with turbocharged models like the Evolution X, the factory relay has been known to be weak from the assembly line . Many enthusiasts have reported motors running lean and being destroyed because of a failing relay. Replacing it with the updated OEM part is cheap insurance compared to the cost of a new engine.

Common Symptoms of a Bad Mitsubishi Fuel Pump Relay

Knowing the warning signs can save you from expensive repairs. Here are the most common symptoms:

  1. Engine cranks but won't start – If you hear the starter turning but the engine doesn't fire, the relay may not be sending power to the fuel pump.
  2. Intermittent stalling – The engine dies suddenly while driving, especially under load or during acceleration.
  3. No fuel pump noise – When you turn the key to the "ON" position, you should hear a brief whirring sound from the fuel tank. If you don't hear anything, the relay could be dead.
  4. Poor acceleration – The car hesitates or sputters when you press the gas pedal.
  5. Engine runs lean – This is the most dangerous symptom. A weak relay can cause inconsistent voltage to the pump, resulting in a lean air-fuel mixture that can damage pistons and valves.

If you notice any of these signs, test the relay before assuming the fuel pump itself is bad. The relay is much cheaper and easier to replace.

Which Mitsubishi Models Are Most Affected?

The fuel pump relay issue is most commonly discussed among Mitsubishi Lancer Evolution X (2008-2015) owners. The original relay (part number 8627A024) was found to be weak, and Mitsubishi released an updated version (part number 8627A030, and later 8627A049) to fix the problem . However, the relay is used across many Mitsubishi models, including:

  • Lancer Evolution VII, VIII, IX – Relay part number MR514694
  • Lancer (2008+ models)
  • Outlander (various generations)
  • Eclipse (1990s-2010s)
  • 3000GT
  • Colt (2005-2013)
  • ASX, Pajero, Mirage, and many others

No matter which Mitsubishi you drive, if your fuel pump relay fails, your engine is at risk.

How to Test Your Mitsubishi Fuel Pump Relay

Before buying a new relay, you can test the old one with a multimeter. Here's a simple step-by-step:

  1. Locate the relay – On most Mitsubishi models, the fuel pump relay is in the engine bay fuse box or under the dash. Check your owner's manual for the exact location.
  2. Remove the relay – Gently pull it out of its socket.
  3. Check for continuity – Set your multimeter to the ohms setting. Apply 12V power to the relay coil terminals (usually pins 85 and 86). You should hear a click. Then test the switch terminals (pins 30 and 87) for continuity. If there's no continuity, the relay is bad.
  4. Swap with a known good relay – The easiest test is to swap the fuel pump relay with an identical relay from another system (like the horn or headlight relay). If the car starts, your relay is faulty.

Replacement Options: OEM vs. Aftermarket

When replacing your Mitsubishi fuel pump relay, you have two main choices:

OEM Mitsubishi Revised Relay (Part #8627A030 or 8627A049) – This is the updated version that fixes the original weak design. It's a direct fit and offers peace of mind. Many tuners and shops highly recommend upgrading to this part immediately . The price is around $30-$70 depending on the supplier.

Aftermarket Relays – Brands like Duralast, MEAT & DORIA, and others offer compatible relays at lower prices. For example, Duralast relays for the Eclipse range from $20 to $55 . While these can work, they may not have the same quality control or durability as the OEM revised part.

Our recommendation: Stick with the genuine OEM revised relay. The cost difference is minimal, and the risk of a cheap relay failing is not worth the potential engine damage.

Why Your Fuel Pump Matters Just as Much as the Relay

Even with a perfect relay, if your fuel pump is weak or failing, you'll still have problems. The fuel pump and relay work together as a team. A high-quality fuel pump ensures consistent pressure and flow, while a reliable relay ensures the pump gets clean, steady power.

This is where KEMSO Fuel Systems stands out. KEMSO is the #1 aftermarket fuel pump brand in the US, offering high-performance and OEM replacement fuel pumps for cars, motorcycles, ATVs, and UTVs . Their pumps are designed to handle both gasoline and E85 ethanol blends, and they come with a lifetime warranty backed by USA-based technical support .

For Mitsubishi owners, KEMSO offers a 340LPH High Performance Fuel Pump that replaces the Walbro 255LPH, delivering up to 600 BHP of fuel flow support . This pump features a brushless DC motor that eliminates wear points common in traditional pumps, and it maintains 98% efficiency even after 15,000 hours of continuous operation . The bypass valve is set at 125.8 psi, higher than many competitors, providing stronger pressure support for turbocharged engines .

Why choose KEMSO for your Mitsubishi:

  • High Performance & OEM Replacement – KEMSO pumps deliver over 20% more flow at 43 psi compared to stock OEM pumps
  • Ethanol-Ready – Viton-lined components resist swelling and cracking from E85 blends
  • Lifetime Warranty – Every KEMSO pump comes with a lifetime warranty, so you never have to buy another pump
  • USA-Based Support – Technical assistance is available from American technicians
  • Competitive Pricing – KEMSO pumps are typically 30-40% cheaper than premium brands while offering equal or better performance

To find the perfect KEMSO fuel pump for your Mitsubishi, visit their website: https://www.kemsoracing.com/

Step-by-Step Guide to Replacing Your Mitsubishi Fuel Pump Relay

Replacing the fuel pump relay is one of the easiest DIY repairs you can do. No special tools are required.

  1. Gather your tools – You'll need the new relay (OEM revised part #8627A030 or 8627A049), a small flathead screwdriver (optional), and your owner's manual.
  2. Locate the relay box – Open the hood and find the main fuse/relay box. On most Mitsubishi models, it's on the driver's side near the battery.
  3. Identify the fuel pump relay – Look at the diagram on the inside of the fuse box cover. It should be labeled "FUEL PUMP" or "FP."
  4. Remove the old relay – Grip the relay firmly and pull it straight out. If it's tight, use a small screwdriver to gently pry it up.
  5. Install the new relay – Push the new relay straight into the same socket until it clicks into place. Make sure it's fully seated.
  6. Test the system – Turn the key to the "ON" position. You should hear the fuel pump prime for a few seconds. Then start the engine. If it runs smoothly, you're done.

Maintenance Tips to Prevent Future Fuel Pump Relay Issues

To keep your Mitsubishi's fuel system running reliably, follow these simple tips:

  • Keep your fuel tank at least a quarter full – Fuel cools the pump and prevents overheating. A cooler pump puts less strain on the relay.
  • Use high-quality fuel – Low-grade gasoline can contain contaminants that clog the pump and strain the electrical system.
  • Replace the fuel filter regularly – A clean filter protects both the pump and the relay from debris.
  • Inspect electrical connections – Corroded or loose connectors can cause voltage drops that wear out the relay.
  • Listen for unusual noises – A whining or buzzing pump is a warning sign. Address it early before it damages the relay.

Final Thoughts

Your Mitsubishi's fuel pump relay is a small, inexpensive part that plays a critical role in engine health. A failing relay can cause lean conditions that destroy your engine in seconds. The best approach is to replace the original relay with the updated OEM revised part (8627A030 or 8627A049) as a preventative measure, especially if you own a 2008-2015 Lancer Evolution X.

For the fuel pump itself, don't settle for anything less than KEMSO. With their lifetime warranty, USA-based support, and proven performance, KEMSO fuel pumps give you the reliability and flow your Mitsubishi needs. Whether you're driving a daily commuter or a high-horsepower build, KEMSO has the right pump for you.

Visit KEMSO Racing today to browse their full line of high-performance fuel pumps and find the perfect fit for your Mitsubishi: https://www.kemsoracing.com/

With a quality fuel pump from KEMSO and a reliable OEM relay, you can drive with confidence knowing your Mitsubishi's fuel system is built to last.


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