2004 Ford Explorer Sport Trac Fuel Pump Replacement: The Complete DIY Guide
If your 2004 Ford Explorer Sport Trac is hard to start, sputters when you step on the gas, or stalls without warning, the fuel pump is likely the culprit. The fuel pump on this truck is an electric unit mounted inside the fuel tank, and it is responsible for pushing pressurized fuel from the tank to the engine. When it begins to fail, the symptoms are usually noticeable long before the truck becomes completely undriveable. Replacing the fuel pump on a 2004 Sport Trac is a moderately involved job that a confident DIY mechanic can handle in a weekend, but it requires careful preparation, the right tools, and a quality replacement part. This guide walks you through everything you need to know about diagnosing a failing pump, choosing the right replacement, and installing it safely.
The 2004 Ford Explorer Sport Trac is equipped with a 4.0L V6 engine, and the fuel pump module assembly is a complete in-tank unit that includes the pump, the fuel level sending unit, a strainer, and the mounting housing. Most owners choose to replace the entire module rather than just the pump itself, because the extra components—especially the sending unit and strainer—can cause problems of their own, and replacing everything at once saves time and effort down the road. The OEM part number for this assembly is 4L2Z-9H307-AC, and it is interchangeable with several other part numbers including 5L2Z-9H307C, E2358M, FG0870, and P76168M.
What You Will Learn in This Guide:
- How to Recognize the Symptoms of a Failing Fuel Pump
- How to Confirm the Diagnosis Before You Buy Anything
- What to Look for When Buying a Replacement Fuel Pump
- Tools and Parts You Will Need for the Job
- A Step-by-Step Installation Guide
- Cost Expectations for Parts and Labor
- Why KEMSO Fuel Pumps Are a Smart Choice for Your Sport Trac
1. How to Recognize the Symptoms of a Failing Fuel Pump
The fuel pump in your 2004 Ford Explorer Sport Trac is designed to last for the life of the vehicle, but like any mechanical component, it can fail over time. The most common warning signs include:
Hard Starting – If the engine cranks for several seconds before firing up, or if it takes multiple attempts to get the truck started, the fuel pump may not be building enough pressure in the fuel lines. This is often the first symptom owners notice.
Sputtering or Hesitation During Acceleration – A failing fuel pump cannot deliver a consistent flow of fuel to the engine. This causes the engine to sputter, hesitate, or stumble when you press the accelerator, especially when going uphill or under heavy load.
Loss of Power While Driving – If the pump is struggling to keep up with the engine's demand, you may notice a general lack of power, particularly at highway speeds. The truck may feel sluggish or unresponsive.
Strange Noises from the Fuel Tank – A healthy fuel pump runs quietly. If you hear a loud whining, humming, or buzzing sound coming from the area around the fuel tank, the pump's motor may be wearing out. The noise is often more noticeable when the tank is low on fuel.
Decreased Fuel Efficiency – A pump that is losing pressure forces the engine to work harder to maintain performance, which can cause a noticeable drop in fuel economy.
Engine Stalling or Dying Completely – In the later stages of failure, the pump may stop working altogether, causing the engine to stall while driving or refuse to start. In some cases, the pump can fail suddenly with no warning at all.
Check Engine Light – A failing fuel pump can cause the air-fuel mixture to run lean, which may trigger the check engine light. If you see this light along with any of the above symptoms, it is worth having the system diagnosed.
2. How to Confirm the Diagnosis Before You Buy Anything
Before you spend money on a new fuel pump, you should confirm that the pump is actually the problem. There are other components in the fuel system that can cause similar symptoms.
Check the Fuel Pump Relay and Fuse – The fuel pump relay is located in the Power Distribution Box under the hood, on the driver's side. A faulty relay or a blown fuse can prevent the pump from receiving power, which mimics the symptoms of a dead pump. Testing the relay is a quick and inexpensive step that can save you from replacing a pump you do not need.
Check the Fuel Filter – A clogged fuel filter can restrict fuel flow and cause many of the same symptoms as a failing pump. If the filter has not been replaced in a long time, swap it out first and see if the problem goes away.
Test Fuel Pressure – The most reliable way to confirm a fuel pump problem is to test the fuel pressure at the fuel rail. You will need a fuel pressure gauge. On a 2004 Sport Trac, the pressure should be within the manufacturer's specified range when the key is turned to the ON position and while the engine is running. If the pressure is low or does not build up at all, the pump is likely failing.
Listen for the Pump Prime – When you turn the key to the ON position without starting the engine, you should hear a brief hum from the fuel tank as the pump primes the system. If you hear nothing, the pump may not be receiving power, or the pump itself may be dead.
If the relay and fuse check out, the fuel filter is fresh, and the fuel pressure is low or nonexistent, you can confidently move forward with a fuel pump replacement.
3. What to Look for When Buying a Replacement Fuel Pump
Choose a Complete Module vs. Pump Only – For the 2004 Ford Explorer Sport Trac, the fuel pump is part of an integrated module that includes the fuel level sending unit, the strainer, and the housing. Replacing the complete assembly is the more reliable option, because it allows you to replace all of the wear-prone components at once. Replacing only the pump requires disassembling the existing module and reusing older components, which can lead to future problems with the sending unit or strainer.
Check the OEM and Interchange Part Numbers – The OEM part number for the 2004-2005 Sport Trac fuel pump module is 4L2Z-9H307-AC. Other compatible part numbers include 4L2Z-9H307AA, 5L2Z-9H307C, E2358M, FG0870, P76168M, PFS400, SP2107M, and F1369A. When shopping online, use these numbers to verify that the part you are buying is the correct one for your truck.
Verify Fitment – Make sure the replacement pump lists the 2004 Ford Explorer Sport Trac 4.0L V6 as a compatible vehicle. The fuel pump module for this truck has a 5-pin electrical connector, and it includes the fuel sending unit. It is also a good idea to check whether the replacement includes a gasket or seal, as some assemblies do not.
Consider the Brand and Warranty – A fuel pump is a critical component, and a cheap, low-quality pump can fail quickly. Look for a brand with a reputation for reliability and a solid warranty. OEM Ford parts are always a safe choice, but quality aftermarket brands can offer comparable performance at a lower price.
4. Tools and Parts You Will Need for the Job
Replacing the fuel pump on a 2004 Ford Explorer Sport Trac involves dropping or lowering the fuel tank, which means you will need a few tools and supplies:
- Floor jack and jack stands
- Fuel pressure gauge (for testing prior to replacement)
- Safety glasses and gloves
- A fire extinguisher rated for fuel fires
- A drain pan or approved fuel storage container
- A fuel line disconnect tool (plastic or metal)
- Socket set and wrenches
- Screwdrivers (flathead and Phillips)
- A pry bar or flat tool for the lock ring
- A new fuel pump module assembly
- A new gasket or seal (if not included with the module)
- Penetrating oil (like WD-40 or PB Blaster)
- A clean rag or shop towels
Important Safety Note: Fuel is highly flammable. Work in a well-ventilated area, keep sparks and open flames away from the work area, and have a fire extinguisher nearby. Always disconnect the negative battery cable before starting work.
5. A Step-by-Step Installation Guide
Replacing the fuel pump on a 2004 Ford Explorer Sport Trac is a job that typically takes 1 to 4 hours, depending on your experience level and whether you encounter any stuck bolts or rusted components. Here is the general process:
Step 1: Relieve the Fuel System Pressure. Locate the fuel pump fuse or relay in the Power Distribution Box and remove it. Start the engine and let it run until it stalls. This depressurizes the fuel system and prevents fuel from spraying out when you disconnect the lines.
Step 2: Disconnect the Negative Battery Cable. This prevents any accidental sparks or electrical shorts while you are working.
Step 3: Raise the Vehicle and Access the Fuel Tank. Use a floor jack and jack stands to raise the rear of the vehicle safely. The fuel tank is located under the rear of the truck, behind the rear axle.
Step 4: Drain the Fuel Tank. Disconnect the fuel line at the tank and drain the fuel into an approved container. The tank should be as empty as possible before you try to lower it, as a full tank is extremely heavy and difficult to handle.
Step 5: Remove the Fuel Tank Straps and Lower the Tank. Support the tank with a floor jack or a transmission jack, then remove the straps that hold the tank in place. Lower the tank slowly and carefully, being mindful of the fuel lines and electrical connectors still attached.
Step 6: Disconnect the Electrical Connector and Fuel Lines. Unplug the electrical connector from the fuel pump module and disconnect the fuel lines using the appropriate disconnect tool. Be prepared for a small amount of fuel to spill.
Step 7: Remove the Old Fuel Pump Module. The fuel pump is secured by a lock ring or retaining ring. Use a pry bar or a flat tool to rotate the lock ring counterclockwise and lift the module out of the tank. Carefully remove the old pump assembly and the gasket.
Step 8: Install the New Fuel Pump Module. Clean the mounting surface on the tank. Place the new gasket in position, then insert the new fuel pump module into the tank. Ensure that the float arm on the sending unit is oriented correctly so it does not catch on the inside of the tank. Rotate the lock ring clockwise to secure the module in place.
Step 9: Reconnect the Fuel Lines and Electrical Connector. Reconnect the fuel lines, making sure they are seated properly and the quick-connect fittings click into place. Plug the electrical connector back into the module.
Step 10: Reinstall the Fuel Tank. Raise the tank back into position and reinstall the straps. Tighten the straps securely, then reconnect the fuel line that you disconnected in Step 4.
Step 11: Reinstall the Fuse or Relay and Reconnect the Battery. Put the fuel pump fuse or relay back in the Power Distribution Box, and reconnect the negative battery cable.
Step 12: Prime the Fuel System and Test. Turn the key to the ON position and listen for the fuel pump to prime. You should hear a brief hum from the tank. Turn the key off, then turn it back on, repeating this a few times to build fuel pressure. Start the engine and check for any fuel leaks around the tank and fuel lines. Let the engine run for a few minutes and verify that the fuel gauge is working correctly.
6. Cost Expectations for Parts and Labor
The cost of replacing the fuel pump on a 2004 Ford Explorer Sport Trac varies depending on where you buy the part and whether you do the work yourself or hire a mechanic.
Parts Only – A complete fuel pump module assembly for the 2004 Sport Trac typically costs between $60 and $150 depending on the brand and where you purchase it. OEM Ford parts are usually at the higher end of that range, while aftermarket brands offer more affordable options.
Labor for Professional Installation – The average national cost for fuel pump replacement across all vehicles is roughly between $611 and $894 including parts and labor. For a 2004 Ford Explorer Sport Trac specifically, the replacement cost has been quoted at around $364 at some mobile service providers, with prices ranging from $259 to $640 depending on location and the specific shop.
DIY Savings – If you replace the pump yourself, you can save several hundred dollars in labor costs. The job is not easy, but it is manageable for someone with basic mechanical skills and the right tools.
7. Why KEMSO Fuel Pumps Are a Smart Choice for Your Sport Trac
When it comes time to choose a replacement fuel pump for your 2004 Ford Explorer Sport Trac, KEMSO is a brand you should seriously consider. KEMSO was founded in Houston, TX in 1999 with the goal of providing high-quality, direct-fit OEM replacement fuel pumps and high-performance fuel system solutions for both the automotive and powersports industries. The company has built its reputation on reliability, performance, and a commitment to customer satisfaction.
High Performance – KEMSO fuel pumps are designed to support higher flow rates than many stock pumps. While the original fuel pump on many vehicles is rated for 60-80 liters per hour (LPH), KEMSO performance pumps can support up to 200 LPH or more, depending on the model. This means your Sport Trac will get a consistent, powerful fuel flow, which supports smoother acceleration and better overall engine responsiveness.
OEM Replacement Quality – KEMSO pumps are engineered to meet or exceed OEM specifications. They are designed to fit perfectly in the original mounting location, with secure plugs that resist vibration and provide stable electrical conductivity. The pump housings are made from high-temperature-resistant materials that are built to last. Every KEMSO pump goes through rigorous quality checks to ensure it performs reliably for years to come.
Lifetime Warranty – One of the biggest advantages of choosing KEMSO is the lifetime warranty that comes with every fuel pump. The company stands behind its products, and if anything goes wrong with your pump, KEMSO will replace it. This kind of warranty gives you peace of mind, knowing that your investment is protected.
Affordable Pricing – KEMSO fuel pumps are priced competitively, with most models retailing at $79.98. This is often significantly less than what you would pay for an equivalent pump at a big-box auto parts store, and the quality is comparable to, if not better than, the original equipment.
Easy Installation – KEMSO fuel pumps are designed for straightforward installation. The connectors are designed to be easy to plug in and secure, and the pump assembly can be easily removed from the fuel tank for inspection or replacement of parts. Whether you are a professional mechanic or a DIY owner, you will appreciate the simplicity of the design.
When you are ready to purchase a replacement fuel pump for your 2004 Ford Explorer Sport Trac, visit KEMSO's website at https://www.kemsoracing.com/ to browse their full selection of high-performance, OEM-quality fuel pumps. You will find reliable parts at competitive prices, backed by a lifetime warranty.
Final Thoughts
Replacing the fuel pump on your 2004 Ford Explorer Sport Trac is not a small job, but it is a necessary one if you want to keep your truck running reliably. The symptoms of a failing pump are clear: hard starting, sputtering, loss of power, and strange noises from the fuel tank. If you catch the problem early and replace the pump with a quality part, you can save yourself from being stranded on the side of the road.
The fuel pump is the heart of your Sport Trac's fuel system. Without it, the engine will not run. A quality replacement from a trusted brand like KEMSO ensures that your truck will start quickly, accelerate smoothly, and provide the reliable performance you expect from a Ford. With a lifetime warranty and prices that are easy on the wallet, KEMSO is a smart choice for any Sport Trac owner.
Do not wait until your truck dies completely. If you are experiencing any of the symptoms described in this guide, test your fuel pressure and inspect your pump today. Then visit https://www.kemsoracing.com/ to find the right KEMSO fuel pump for your 2004 Ford Explorer Sport Trac. Your truck will thank you.