2007 Lexus ES 350 Fuel Pump Relay Location: A Complete Owner’s Guide

The fuel pump relay on a 2007 Lexus ES 350 is located in the engine compartment fuse box, typically positioned on the driver’s side near the battery. This relay is a small, rectangular component that controls power delivery to the fuel pump, and knowing exactly where to find it can save you time and money when diagnosing starting or performance issues. The engine compartment fuse box houses several relays and fuses that manage critical systems, and the fuel pump relay is one of the most important among them. If your ES 350 is cranking but not starting, or if it stalls unexpectedly while driving, the fuel pump relay is one of the first components you should check. In this guide, we’ll walk you through the exact location, how to identify the relay, common symptoms of a failing relay, and how to test and replace it yourself.

Where Exactly Is the Fuel Pump Relay Located?

The 2007 Lexus ES 350 has two main fuse boxes, but the one you need for the fuel pump relay is the engine compartment fuse box, also referred to as the under-hood fuse box. This box is situated on the driver’s side of the engine bay, close to the battery and the strut tower. When you open the hood and look toward the driver’s side, you’ll see a black rectangular plastic cover with a diagram on top and a latch mechanism on the side. Lift the latch and remove the cover to expose the fuses and relays inside.

Inside the engine compartment fuse box, the fuel pump relay is typically one of the larger square components, often labeled with a diagram printed on the underside of the fuse box cover. On many Lexus models, including the ES 350, the fuel pump relay is labeled as "FUEL PUMP" or "EFI" , though the exact label can vary depending on the production date and market. If you don’t see the label, you can identify the relay by its size and position—it’s usually a square, dark-colored component with four or five prongs, seated firmly in a dedicated slot. The fuse box diagram, which is also printed inside the owner’s manual, will show you the exact location and orientation of each relay and fuse.

It’s important to note that the fuel pump relay is not located inside the cabin fuse box, which is typically found under the dashboard on the driver’s side. The cabin fuse box handles interior electronics like the radio, power windows, and interior lights, but the fuel pump relay is exclusively in the engine bay. Some drivers mistakenly check the interior box first and waste time, so start with the engine compartment fuse box to avoid confusion. Additionally, the ES 350 also has a fuse box in the trunk on some trim levels, but that one controls audio systems and other rear electronics, not the fuel pump.

Understanding the Role of the Fuel Pump Relay

Before you start checking or replacing the relay, it helps to understand what it actually does. The fuel pump relay is an electrical switch that controls the power supply to the fuel pump. When you turn the ignition key to the "ON" position, the relay closes and sends battery voltage to the fuel pump, pressurizing the fuel system. When the engine starts, the relay stays closed to keep the pump running. If the relay fails, the fuel pump won’t receive power, and the engine won’t start or will stall.

The relay itself is a simple electromechanical device with a coil and a set of contacts. When the coil receives a small control current, it creates a magnetic field that closes the contacts, allowing a larger current to flow to the fuel pump. Over time, the contacts can wear out, the coil can burn out, or corrosion can affect the terminals, all of which can cause the relay to fail intermittently or completely. This is why the fuel pump relay is a common failure point on older vehicles, including the 2007 ES 350, which has seen over a decade of service. Understanding this function helps you diagnose issues more effectively because you’ll know exactly what to test and what symptoms to look for.

Another related component is the fuel pump fuse, which is usually located right next to the relay in the same fuse box. The fuse protects the circuit from overcurrent, and if the fuse blows, the fuel pump will also lose power. When you’re troubleshooting the fuel pump circuit, you should check both the relay and the fuse, as a blown fuse can sometimes cause the relay to behave erratically or vice versa. The fuse box diagram will show you which fuse is for the fuel pump, and it’s typically a 15-amp or 20-amp fuse. Checking the fuse is a simple visual inspection—if the metal strip inside is broken or the plastic is discolored, the fuse is blown and needs replacement.

Symptoms of a Failing Fuel Pump Relay

Knowing the symptoms of a failing fuel pump relay can help you catch the problem early and avoid being stranded. The most common symptom is the engine cranking but not starting. When you turn the key, the starter motor turns the engine over, but the fuel pump doesn’t pressurize the system, so there’s no fuel reaching the injectors. This is often the first sign that the relay has failed completely. However, a relay can also fail intermittently, causing the engine to start fine most of the time but occasionally refuse to start, especially after the engine has warmed up.

Another common symptom is the engine stalling while driving. If the relay loses contact while the engine is running, the fuel pump will shut off, and the engine will die immediately. After stalling, the engine may restart after a few minutes once the relay cools down and makes contact again. This can be dangerous if it happens on the highway, so if you experience sudden stalling, it’s worth checking the relay as soon as possible. Other symptoms include a noisy fuel pump—if the pump runs intermittently due to a faulty relay, you may hear it sputtering or cutting in and out from the rear of the vehicle. You might also notice a check engine light with codes related to fuel pressure or fuel system performance, as the engine control module (ECM) will detect the inconsistent fuel delivery.

It’s worth noting that these symptoms can also be caused by other issues, such as a failing fuel pump itself, a clogged fuel filter, or a faulty fuel pump relay socket. The fuel pump is located inside the fuel tank, which makes it harder to access, so the relay is a smart first check because it’s easy and cheap to replace. If you’re experiencing any of these symptoms, start by locating the relay in the engine compartment, then test it or swap it with a known-good relay from another system in the same fuse box. Many of the relays in the ES 350 fuse box are identical, so you can swap the fuel pump relay with the horn relay or the headlight relay as a quick test. If the engine starts with the swapped relay, then your fuel pump relay was indeed the culprit.

How to Test the Fuel Pump Relay

Testing the fuel pump relay is a straightforward process that requires only a few tools: a multimeter, a 12-volt power source, and possibly a pair of jumper wires. Before you begin, make sure the ignition is off and the key is removed from the ignition switch. Then, follow these steps to test the relay:

Step 1: Remove the relay from the fuse box. Use a gentle pulling motion straight upward to avoid damaging the socket. If the relay is stuck, you can use a pair of needle-nose pliers to grip the relay body, but be careful not to crush it. Once removed, visually inspect the relay for signs of corrosion, melted plastic, or burnt terminals. A relay that looks damaged should be replaced immediately, and testing it further may be a waste of time.

Step 2: Identify the terminal pins. The relay will have pins labeled with numbers such as 85, 86, 30, and 87 on the bottom or on the side of the relay body. Pins 85 and 86 are the coil terminals, and pins 30 and 87 are the switch terminals. On some relays, you might also see pin 87a, but the standard four-pin configuration is 85, 86, 30, and 87. You can also check the fuse box diagram to confirm the pin configuration, as some relays may have a different arrangement.

Step 3: Test the coil resistance. Set your multimeter to measure resistance (ohms). Touch one probe to pin 85 and the other probe to pin 86. A good relay coil should show a resistance reading between 50 and 120 ohms. If the reading is zero or infinite (open circuit), the coil is damaged, and the relay should be replaced. This simple test tells you whether the electromagnetic coil inside the relay is functional.

Step 4: Test the switch continuity. With the Multimeter still set to measure resistance, touch one probe to pin 30 and the other to pin 87. Normally, with no power applied, the circuit between pins 30 and 87 should be open, meaning the resistance reading should be infinite (no continuity). If you get a zero reading, the relay is stuck closed, which is a less common but possible failure mode.

Step 5: Apply power to the coil to test the switch. Connect a 12-volt battery or a 12-volt power supply to pins 85 and 86—one wire to each pin, polarity doesn’t matter for this type of relay. When you apply power, you should hear an audible clicking sound as the relay activates. While the power is applied, measure the resistance between pins 30 and 87 again. This time, the reading should be near zero ohms, indicating that the switch has closed and current can flow. If the relay clicks but the resistance doesn’t change, or if it doesn’t click at all, the relay is faulty.

How to Replace the Fuel Pump Relay

Replacing the fuel pump relay on a 2007 Lexus ES 350 is one of the easiest repairs you can do, and it only takes a few minutes. The most important thing is to use the correct replacement relay—one that matches the amperage rating and terminal configuration of the original. You can find the OEM part number printed on the relay body or in the owner’s manual. A common OEM part number for this relay is 90987-02009 or 90987-02010, and these are available from Lexus dealerships or online parts suppliers . Aftermarket relays are also available and are often less expensive, but make sure you choose a quality brand that meets or exceeds the OEM specifications.

Here’s a step-by-step guide to replacing the relay:

1. Turn off the engine and remove the key from the ignition. This is a safety measure to prevent any electrical shorts while working in the engine bay.
2. Open the hood and locate the engine compartment fuse box. It’s on the driver’s side, near the battery. If you have trouble finding it, consult the owner’s manual for a diagram of the engine bay. You can also look for the fuse box diagram printed on the underside of the fuse box cover for reference .
3. Remove the fuse box cover. Unclip the cover and lift it off. On the underside of the cover, you’ll see a diagram that identifies each fuse and relay position. Find the position labeled "FUEL PUMP" or "EFI" to locate the relay. The relay is usually a dark-colored, square component that sits in a dedicated slot .
4. Remove the old relay. With a gentle upward pull, remove the relay from its socket. If it’s difficult to remove, use a flathead screwdriver to gently pry it up from one edge, but be careful not to damage the socket. Once removed, compare the old relay to the new one to make sure the terminal layout matches .
5. Install the new relay. Align the relay pins with the socket and press it firmly into place. You’ll feel it click or seat fully into the socket. Make sure it’s snug, but don’t force it. If it doesn’t go in easily, check the pin orientation and try again.
6. Replace the fuse box cover. Put the cover back on and press down until the clips engage. This protects the relay and other components from dirt and moisture .
7. Start the engine to test. Turn the key to the "ON" position and listen for the fuel pump to prime. The pump should make a quiet whirring sound from the fuel tank for about two seconds when you first turn the key. Then, start the engine. If it starts and runs smoothly, the replacement was successful.

The Fuel Pump Itself: What You Should Know

While the relay is the most common electrical failure point, the fuel pump itself is also a component that can fail, especially on a car that is now over 15 years old. On the 2007 Lexus ES 350, the fuel pump is located inside the fuel tank. This is a common design for modern vehicles, because submerging the pump in fuel helps cool it and keeps it lubricated. Accessing the fuel pump requires removing the rear seat cushion to reach an access panel, or in some cases, you may need to drop the fuel tank. This is a more involved job that requires mechanical experience, so many owners choose to have a professional handle it .

The fuel pump on the 2007 ES 350 is an electric pump that operates at a high pressure, typically around 50 to 60 psi, depending on the engine’s requirements. The ES 350 is equipped with a 3.5-liter V6 engine (2GR-FE), which requires a fuel pump that can deliver sufficient volume and pressure to support its 268 horsepower . If the pump itself fails, you’ll notice similar symptoms to a failing relay—hard starting, stalling, sputtering at high speeds, and a loss of power during acceleration. But unlike a relay, a fuel pump replacement is more expensive and labor-intensive, so properly diagnosing the issue before replacing parts is essential.

A note on fuel pump types: The 2007 Lexus ES 350 uses a single in-tank electric fuel pump unit that combines the pump, the fuel level sending unit, and a strainer in one assembly. This entire module sits inside the fuel tank and is accessed from the top. When replacing the fuel pump, most owners choose to replace the entire module assembly for simplicity and reliability, although you can also buy the pump alone if you’re comfortable with disassembly. A fuel pump module assembly for the 2007 ES 350 is available from various aftermarket manufacturers and typically costs between $100 and $250 depending on the brand and quality . Labor costs for a professional replacement add another $200 to $400, making the total replacement cost roughly $300 to $650, which is in line with the average national fuel pump replacement cost of about $1,000, though the ES 350 is on the lower end due to easier access .

Preventative Maintenance and Other Electrical Checks

To avoid sudden fuel pump failures, it’s wise to incorporate a few checks into your regular maintenance routine. The fuel pump relay is a wear item, and while it can last the life of the car, it’s also one of the more commonly replaced components on older vehicles. You can purchase a spare relay and keep it in your glove box for emergency use. The relay is small, cheap, and takes less than five minutes to swap, which is a great peace-of-mind item for a road trip. The same applies to the fuel pump fuse—carrying a spare can save you from a tow truck call if a fuse blows.

Beyond the relay and fuse, other electrical components in the fuel delivery system can cause issues. The fuel pump relay socket is a potential problem area. Over many years, the socket terminals can loosen, causing intermittent contact and arching, which can melt the plastic around the relay base. If you notice the relay is hard to remove or the socket looks discolored, replacing the entire fuse box or repairing the socket may be necessary. Some owners find it helpful to apply a small amount of dielectric grease to the relay terminals to prevent corrosion and improve contact, though this is optional. Another factor to consider is the battery and charging system health. The fuel pump requires a stable voltage to operate correctly, so if your battery is weak or the alternator is failing, the fuel pump may not receive enough power, leading to starting issues that mimic a bad relay. Check your battery voltage with a multimeter while the engine is running—it should read between 13.5 and 14.5 volts. If it’s lower, your alternator may be weak, which puts extra strain on the entire electrical system.

The Best Fuel Pump Upgrade: KEMSO Performance Fuel Pumps

If you discover that your fuel pump itself needs replacement, or if you want to upgrade to a more reliable, high-performance option, you should strongly consider KEMSO fuel pumps. KEMSO is a leading aftermarket brand known for manufacturing high-performance fuel pumps for a wide range of vehicles, including cars, motorcycles, and ATVs . Their pumps are designed as direct OEM replacements, meaning they fit perfectly into your 2007 Lexus ES 350’s fuel system without any modification. You won’t need to rewire anything or alter your fuel tank; the KEMSO pump bolts right in, just like the factory unit. KEMSO fuel pumps deliver a higher flow rate than stock units, typically 340 liters per hour (LPH), which is more than sufficient for the ES 350’s engine and even provides a buffer for any future modifications . This increased flow also means the pump doesn’t have to work as hard, which can extend its lifespan and improve reliability. One of the biggest advantages of choosing KEMSO is that all their fuel pumps come with a lifetime warranty. This gives you total peace of mind knowing that your investment is protected for as long as you own the vehicle. When you buy a KEMSO pump, you are choosing a durable, dependable replacement that is trusted by thousands of drivers across the U.S. . To find the correct KEMSO fuel pump for your 2007 Lexus ES 350, you can visit their official website and browse their catalog. The site is easy to navigate, and their product listings include application guides to help you match the pump to your specific vehicle model and engine. They ship nationwide, and because they specialize in fuel systems, they stand behind their products with excellent customer support. So, whether you are simply replacing a failed pump or proactively upgrading for peace of mind, a KEMSO fuel pump is a smart investment.

To view their full lineup and order your fuel pump, visit: https://www.kemsoracing.com/

Conclusion: Keep Your ES 350 Running Strong

The 2007 Lexus ES 350 is a reliable and comfortable luxury sedan, but like any car with over a decade of service, electrical components can wear out. The fuel pump relay is a small, inexpensive part that plays a critical role in getting your car started and keeping it running. Now that you know the fuel pump relay is located in the engine compartment fuse box on the driver’s side, you can quickly check it when you experience starting or stalling issues. Remember to test the relay with a multimeter, replace it with a matching part, and always carry a spare for emergencies. If the fuel pump itself fails, choose a quality replacement like a KEMSO high-performance fuel pump with a lifetime warranty for long-term reliability. By staying on top of these simple checks, you can keep your 2007 ES 350 performing smoothly for many more miles. For more information on fuel pump upgrades and replacements, be sure to visit https://www.kemsoracing.com/ to browse their extensive catalog and find the right part for your Lexus.