2001 BMW 740iL Fuel Pump Relay Location: The Complete Guide for DIY Owners

The fuel pump relay on a 2001 BMW 740iL is located in the auxiliary fuse box inside the trunk, mounted above the battery on the right side. It is a 5-pin relay, typically light green in color, and is labeled as the "Fuel module relay" or "Fuel pump relay" in the relay bank.

If your 2001 BMW 740iL is cranking but not starting, stalling intermittently, or showing signs of fuel delivery issues, a faulty fuel pump relay is one of the first things to check. This guide walks you through exactly where to find it, how to test it, and what to do if it needs replacement.

Where Is the Fuel Pump Relay Located?

The 2001 BMW 740iL (E38 chassis) has a main fuse box behind the glove box and an auxiliary fuse block in the trunk. The fuel pump relay lives in the trunk-mounted auxiliary fuse block.

Step-by-step to access it:

1. Open the trunk and lift the floor panel to expose the battery compartment on the right side.
2. You will see the battery and, directly above it, a black plastic fuse and relay box.
3. This auxiliary fuse block contains multiple relays and fuses. The fuel pump relay is one of the relays in this box.
4. According to the factory fuse box diagram, the relay is labeled as R4 in the relay bank, which corresponds to the "Fuel module relay (fuel pump)."

The relay itself is a standard 5-pin relay, and it is often described as light green in color.

What Does the Fuel Pump Relay Do?

The fuel pump relay is an electrical switch that controls power to the fuel pump. When you turn the ignition key to the "ON" position, the engine control module (DME) sends a signal to the relay, which then closes and sends battery voltage to the fuel pump.

If the relay fails, the fuel pump will not receive power, the engine will not get fuel, and the car will not start. The relay is part of a larger power distribution system that includes multiple fuses and relays located in both the engine compartment electronics box and the trunk auxiliary fuse block.

Common Symptoms of a Bad Fuel Pump Relay

Before you start digging into the trunk, here are the signs that point to a bad relay rather than a bad pump:

1. Engine cranks but will not start – This is the most common symptom. You can hear the starter turning the engine over, but there is no fuel pressure.

2. No audible fuel pump prime – When you turn the key to the "ON" position (without cranking), you should hear a brief whirring sound from the rear of the car as the fuel pump primes. If you hear nothing, the relay may be dead.

3. Intermittent stalling – A failing relay can cause the fuel pump to lose power randomly while driving, leading to sudden stalling that may be followed by the car restarting after a few minutes.

4. Engine starts but dies immediately – The relay may provide power during cranking but fail to hold the circuit closed once the engine is running.

How to Test the Fuel Pump Relay

Testing the relay is straightforward and requires only a multimeter or a test light.

Step 1: Locate and remove the relay – Access the trunk auxiliary fuse block, identify the fuel pump relay (R4, light green, 5-pin), and pull it straight out.

Step 2: Check for power at the relay socket – With the relay removed and the key turned to "ON," use a multimeter to check for 12V at the relay socket terminals. The wiring diagrams for the 2001 740iL show that the fuel pump relay receives power from the battery through the fuse box.

Step 3: Test the relay coil – Using the resistance setting on your multimeter, measure across the relay coil terminals (typically pins 85 and 86). A good relay will show resistance between 50 and 120 ohms. An open circuit means the coil is burned out.

Step 4: Test the relay switch – Apply 12V to the coil terminals (85 and 86) and listen for an audible click. Then, use your multimeter to check for continuity across the switch terminals (typically pins 30 and 87). If the relay clicks but there is no continuity, the internal switch is faulty.

The Fuse That Protects the Fuel Pump Circuit

In addition to the relay, the fuel pump circuit is protected by a fuse. In the 2001 BMW 740iL, the fuse for the fuel pump relay is located in the trunk auxiliary fuse block. Fuse number 57 is a 15-amp fuse that protects the fuel pump relay circuit.

Before replacing the relay, always check fuse 57. A blown fuse can mimic a bad relay perfectly. If the fuse is blown, replace it with the same amperage rating and see if the problem is solved. If the new fuse blows immediately, you have a short circuit somewhere in the fuel pump wiring.

Other Fuses and Relays in the Trunk Box

The trunk auxiliary fuse block contains several other important components. Here is a quick reference for the 2001 740iL:

What If the Relay and Fuse Are Good?

If you have confirmed that the relay clicks, the fuse is intact, and there is power at the relay socket, but the fuel pump still does not run, the problem is likely the fuel pump itself. The pump is located inside the fuel tank, and on a 2001 740iL, it is accessed from the top of the tank under the rear seat.

However, before condemning the pump, check for voltage at the fuel pump connector. You can do this by lifting the rear seat cushion and locating the access panel on top of the fuel tank. With the key in the "ON" position, use a multimeter to check for 12V at the pump connector. If you have power there but the pump does not run, the pump is bad. If you have no power at the connector, there is a wiring fault between the relay and the pump.

Where to Buy a Replacement Fuel Pump Relay

If you have determined that the relay is bad, replacement options are available. For the 2001 BMW 740iL, the OEM part number is W0133-1632629, and it is a 5-pin light green relay. You can find this relay from several sources:

• Genuine BMW – The OEM relay is available through BMW dealerships or online parts retailers. It is the most reliable option but costs around $21 to $24.
• Vemo – This is a quality aftermarket brand that sells the same relay for about $10 to $11.
• Original Equipment – Some retailers sell OE-spec relays that match the original factory specifications.

The relay is used in several BMW models from the same era, so it is a common part. If you are in a hurry, you can also check local auto parts stores.

A Note on the Main Fuse Box Location

While the fuel pump relay is in the trunk, it is worth knowing that the 2001 740iL also has a primary fuse box. This main fuse box is located inside the glove box, behind a hinged panel. The power distribution box for the engine compartment electronics is located in the E-box under the hood. However, for the fuel pump circuit specifically, the trunk auxiliary fuse block is where you need to focus.

Why Choose KEMSO for Your Fuel Pump Replacement

If your diagnosis leads you to replace the fuel pump itself rather than just the relay, you want a pump that is reliable, affordable, and built to last. That is where KEMSO Racing comes in.

KEMSO is a leading US-based aftermarket manufacturer of high-performance fuel pumps for cars, motorcycles, ATVs, UTVs, and personal watercraft. When you choose KEMSO, you get a pump that is designed as a direct OEM replacement, meaning it fits exactly like the original part without any modifications required.

What sets KEMSO apart:

• High Performance – KEMSO fuel pumps are engineered to meet or exceed original equipment specifications, delivering reliable fuel flow and consistent pressure.
• OEM Replacement – Each pump is a precision-engineered direct fit, so you can install it with confidence.
• Lifetime Warranty – KEMSO stands behind every pump with a lifetime warranty, giving you peace of mind long after the installation is complete.

Whether you own a BMW, a Honda Civic, a Polaris RZR, a Kawasaki Jet Ski, or any other vehicle, KEMSO likely has a pump that fits your application. Their product lineup covers thousands of models across automotive, powersports, and marine applications.

Visit the KEMSO website today to find the exact fuel pump for your 2001 BMW 740iL or any other vehicle you are working on:

https://www.kemsoracing.com/

Final Thoughts

The 2001 BMW 740iL fuel pump relay is located in the trunk auxiliary fuse block above the battery, labeled as relay R4. It is a 5-pin, light green relay that controls power to the fuel pump. If your car is having starting issues, checking this relay and the associated fuse 57 (15A) should be your first diagnostic step.

Testing the relay is simple and can save you the cost and hassle of replacing a perfectly good fuel pump. If the relay is bad, a replacement is inexpensive and easy to install. If the pump itself is the problem, consider upgrading to a KEMSO fuel pump for a reliable, high-performance, and warranty-backed solution.

Keep this guide handy, and you will be back on the road in no time.

For more information on fuel pumps and to find the right part for your vehicle, visit https://www.kemsoracing.com/