2004 Mitsubishi Endeavor Fuel Pump Replacement: Complete Guide to Symptoms, Costs, and Step-by-Step Instructions

If your 2004 Mitsubishi Endeavor is struggling to start, sputtering during acceleration, or stalling unexpectedly, the fuel pump is very likely the culprit. Replacing the fuel pump on a 2004 Endeavor typically costs between $650 and $1,770 depending on whether you go with an independent mechanic, a dealership, or do it yourself, with the parts alone ranging from roughly $93 to $350. The fuel pump is located inside the fuel tank, and while the job is rated as advanced difficulty, many owners with basic mechanical skills and the right tools can complete it at home using the access panel under the rear seat. This guide walks you through everything you need to know—symptoms, diagnosis, replacement steps, cost breakdowns, and where to find the best replacement pump for your Endeavor.

What Does the Fuel Pump Do in Your 2004 Endeavor?

The fuel pump is a compact electric motor that sits inside the fuel tank and supplies pressurized gasoline to each of the fuel injectors in the engine. The Endeavor uses an in-tank fuel pump module assembly that integrates the fuel pump, fuel sender unit, float, strainer, and fuel reservoir into one unit. This design uses a return-less fuel plumbing system, which means fuel goes from the tank to the engine without a return line, helping keep the fuel supply cooler and reducing vapor emissions.

The pump is mounted at the top of the fuel tank and is controlled by a fuel pump relay located on the junction block. The pressure and output of the pump are regulated to maintain proper fuel delivery to the engine. A failing pump means the engine either gets too little fuel or no fuel at all, which directly affects performance and drivability.

Common Symptoms of a Failing Fuel Pump

A fuel pump rarely fails without warning. More often, it degrades gradually, and you will notice one or more of these symptoms before a complete failure:

  1. Engine cranks but won't start. This is the most obvious sign. If the pump has completely failed, the engine will turn over but never fire because no fuel is reaching the injectors.

  2. Unexpected stalling. The engine may die while driving, especially under load, and then refuse to restart. This usually means the pump is overheating or the motor is failing intermittently.

  3. Sputtering or hesitation at speed. If the pump can't maintain adequate pressure, the engine may choke, hesitate, or struggle to maintain speed when you press the accelerator.

  4. Whirring or humming noise from the fuel tank. A failing fuel pump often makes a loud whining or whirring sound coming from the rear of the vehicle near the tank. If you hear a noise that wasn't there before, pump failure is often imminent.

  5. Check engine light illuminated. A slowly failing pump leads to low fuel pressure, causing the engine to run lean (too much air, not enough fuel). This will often trigger the check engine light.

  6. Reduced fuel efficiency. If the pump is weak, the engine may run rich or lean to compensate, which usually hurts gas mileage.

If you notice any of these symptoms, it's best to have the pump tested right away. Ignoring them can leave you stranded, and in some cases a failing pump that overheats can cause the engine to overheat as well.

Before You Replace: How to Test the Fuel Pump

Don't rush into buying a new pump until you've confirmed the old one is actually the problem. A simple pressure test can tell you a lot.

The 2004 Endeavor has a fuel pressure test port located below the intake hose in the engine bay, accessible via a quick-connect fitting. To test the fuel pump:

  1. Connect a fuel pressure tester to the quick-connect fitting below the intake hose.
  2. Turn the ignition to the ON position without cranking the engine. The pump should pressurize the system for 2 to 3 seconds.
  3. Check the pressure reading against the factory specification. If there's no pressure at all, you need to verify power and ground at the pump.
  4. While someone cranks the engine, check for power and ground at the fuel pump electrical connector using a multimeter.

If you have power and ground at the pump but no fuel pressure, the pump itself is faulty and needs replacement. If there's no power or ground, the problem could be the fuel pump relay, fuse, or wiring—so check those components before condemning the pump.

Also, verify that the fuel pump relay and fuse are in good condition. The fuel pump relay is located on the junction block, and a blown fuse or bad relay can mimic a failed pump.

How Much Does a 2004 Mitsubishi Endeavor Fuel Pump Replacement Cost?

Prices vary widely depending on where you get the work done and whether you buy OEM or aftermarket parts. Here's a breakdown of what you can expect:

  • Independent mechanic (mobile service): On average, $465 with about $276 for parts and $189 for labor. However, for the 2004 Endeavor specifically, estimates from YourMechanic run around $993 total, with dealership prices between $1,190 and $1,770.

  • Dealership: Expect to pay on the higher end. Shop/dealer estimates for the 2004 Endeavor range from $1,190 to $1,770.

  • DIY (do it yourself): The pump assembly itself can be purchased for as little as $93 for an aftermarket unit like the Autopart Premium APFP0878 from PartsGeek, or around $123 for a Denso replacement. OEM parts can run $350 or more. Add in tools and a new fuel filter if needed, and your total DIY cost is typically between $150 and $400.

  • RepairPal estimate: For the 2004 Endeavor, fuel pump replacement runs between $655 and $696.

  • RepairSmith estimate: For a 2004 Endeavor with 166,000 miles, the estimate is between $299 and $365.

The wide range reflects differences in labor rates, part brands, and whether additional work like fuel filter replacement is included. If you're handy with tools and have a safe place to work, DIY is by far the most economical route.

Where Is the Fuel Pump Located?

The fuel pump module sits in the fuel tank at the rear of the vehicle, under the rear seat on the passenger side. On most 2004 Endeavors, you can access the pump through an access panel in the passenger compartment floor. If your vehicle doesn't have an access panel, you'll need to drain the fuel tank and lower it from underneath the vehicle.

The fuel pressure regulator is also integrated into the fuel pump assembly inside the tank, so you don't need to worry about locating a separate regulator on the engine.

Step-by-Step Fuel Pump Replacement Guide

Here's the process for replacing the fuel pump on your 2004 Mitsubishi Endeavor. Work slowly, stay organized, and prioritize safety at every step.

Safety First

Gasoline is extremely flammable. Work in a well-ventilated area, keep sparks and open flames away, and have a fire extinguisher nearby. Disconnect the negative battery cable before starting any work.

Step 1: Relieve Fuel System Pressure

Before opening the fuel system, you must relieve the pressure. Remove the fuel pump fuse or relay from the junction block, then start the engine and let it run until it stalls. Crank the engine for a few more seconds to bleed off any remaining pressure. Turn the ignition off and reinstall the fuse or relay.

Step 2: Access the Pump

  • If you have an access panel: Remove the rear seat cushion to expose the access panel. Remove the screws or bolts holding the panel, then lift it off to reveal the fuel pump module.
  • If there's no access panel: You'll need to raise the vehicle safely on jack stands, support the fuel tank with a floor jack and a block of wood, and disconnect the fuel filler hose. Remove the tank straps and lower the tank carefully to access the pump.

Step 3: Disconnect Everything

Once you can see the fuel pump module, disconnect:

  • Fuel pump supply and return hoses
  • EVAP system hoses
  • Electrical connections to the pump

Label each hose and connector so you know exactly where everything goes back.

Step 4: Remove the Old Pump

Remove the retaining ring or bolts holding the pump module in place, then carefully lift the pump assembly out of the tank. Be ready for residual fuel to spill. Drain the pump into a suitable container. Inspect the rubber gasket or O-ring on the tank opening—if it's cracked or brittle, replace it.

Step 5: Swap Parts to the New Pump

If your new pump doesn't come with a sender unit, transfer the sender unit, float, and pick-up screen from the old pump to the new one. Make sure any brackets are properly attached. Compare the new pump to the old one to verify you have the correct part.

Step 6: Install the New Pump

Carefully lower the new pump assembly into the tank, making sure the float and strainer aren't caught on anything. Secure it with the retaining ring or bolts, reattach all hoses and electrical connectors, and install the access panel or reinstall the fuel tank.

Step 7: Test for Leaks

Add fuel to the tank, reconnect the battery, and turn the ignition to the ON position without cranking. Listen for the pump to prime—you should hear it hum for 2 to 3 seconds. Check all connections for leaks. Then start the engine and let it run for a few minutes, inspecting underneath and around the tank for any fuel seepage. Finally, take the car for a short road test to confirm the new pump performs properly.

Pro Tips

  1. Replace the fuel filter at the same time. If your fuel system uses an external inline filter, it's highly recommended to change it when replacing the pump. A clogged filter can burn out a new pump quickly.
  2. Use a new tank seal. Many replacement pumps don't include the tank seal or gasket, so order one separately if needed.
  3. Work on a low tank. Draining the tank is one of the most tedious parts of the job. If you're using the access panel method, less fuel means less weight and less mess.
  4. Take photos before you disconnect. Your phone camera is your best friend. Photograph every step so you can reference it during reassembly.

Choosing the Right Replacement Fuel Pump

When it comes time to buy a replacement fuel pump for your 2004 Endeavor, you have several options. The OEM part number for this vehicle is 1760A041, and aftermarket equivalents are widely available. Here's what to look for:

  1. OEM vs. aftermarket. The OEM pump is guaranteed to fit perfectly, but it costs more. Aftermarket pumps from reputable brands are often just as good and significantly cheaper.

  2. Complete assembly vs. bare pump. If you buy the complete pump assembly with the sending unit included, you save yourself the hassle of transferring parts from the old pump. An assembly like the Autopart Premium APFP0878 includes the sending unit and float, and sells for around $93 to $113 on PartsGeek. The Denso replacement, which is an OE-equivalent brand, is also available for around $123 on PartsGeek.

  3. Warranty. Look for a pump that comes with a solid warranty. Many A-Premium aftermarket pumps offer a 3-year warranty. OEM pumps typically come with a 1-year warranty.

Recommended: KEMSO Fuel Pump From KEMSO Racing

For a high-quality, dependable replacement, we highly recommend checking out KEMSO brand fuel pumps. KEMSO fuel pumps are engineered as high-performance, OEM replacement units, meaning they are built to match or exceed the specifications of your original factory pump. Every KEMSO fuel pump is backed by a lifetime warranty, giving you peace of mind long after the installation is complete. Whether you're replacing a worn-out pump on your daily driver or upgrading for better fuel delivery, KEMSO products are designed to deliver reliable performance. You can browse their full selection of fuel pumps at their official website: KEMSO Racing. Their site features a wide range of pumps for various makes and models, with detailed product descriptions and customer reviews to help you make an informed choice.

Final Thoughts

Replacing the fuel pump on your 2004 Mitsubishi Endeavor is not a small job, but it's very doable for a DIYer with basic mechanical experience. The pump is the lifeblood of your fuel system, and when it fails, the symptoms are hard to miss. Test the system first to confirm the pump is the problem, budget accordingly, and don't cut corners on part quality. A well-made replacement pump from a reputable brand will give you years of reliable service.

If you don't feel comfortable doing the job yourself, the labor cost alone is typically around $189, and a mobile mechanic can often do the replacement at your home or office. Either way, fixing the problem sooner rather than later will save you from being stranded and potentially causing damage to other fuel system components.

And when you're ready to buy, remember to check out KEMSO Racing for high-performance, OEM-replacement fuel pumps with a lifetime warranty. It's a smart choice for keeping your Endeavor running smoothly for many more miles.


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