2010 Buick LaCrosse Fuel Pump Relay Location: The Complete Owner's Guide

The fuel pump relay on a 2010 Buick LaCrosse is located in the under-hood fuse box on the driver's side of the engine compartment. This small electrical component controls power flow to the fuel pump, and knowing exactly where it sits can save you hours of frustration when your car won't start. In most GM vehicles of this generation, the relay sits inside the main fuse box near the battery, labeled clearly on the fuse box cover diagram. Once you open that black plastic cover, you will spot a small rectangular component with four or five metal prongs that clicks when you turn the ignition key. That is your fuel pump relay, and this guide walks you through everything you need to know about finding it, testing it, and replacing it.

Why the Fuel Pump Relay Matters in Your LaCrosse

The fuel pump relay is a basic electrical switch that controls the power supply to the fuel pump located inside your fuel tank. When you turn the ignition key to the "on" position, the relay receives a signal from the vehicle's computer and activates, allowing electrical current to reach the fuel pump motor. This pressurizes the fuel system so the engine can start and run properly.

Without a functioning relay, your fuel pump will not receive power, and your engine will crank but never fire up. Understanding where this relay lives and how to test it is one of the simplest diagnostic steps you can perform before spending money on costly parts or a mechanic visit.

The Quick Answer: Where to Find It

For a 2010 Buick LaCrosse, follow these steps to locate the fuel pump relay:

  1. Open the hood and look toward the driver's side of the engine bay. You will see a black plastic fuse box mounted near the battery.
  2. Remove the fuse box cover by pressing the release tabs on the sides and lifting it straight up.
  3. Look at the underside of the cover. The fuse box cover has a diagram printed on it showing the location and function of each fuse and relay. Find the label that says "Fuel Pump" or "FP."
  4. Identify the relay. The fuel pump relay is a small, cube-shaped component with a gray or black plastic housing. It will be plugged into a socket in the fuse box alongside several fuses.

The relay is typically tucked toward the rear section of the fuse box, near the firewall side. If the diagram is worn or hard to read, you can check the owner's manual for the fuse and relay layout chart.

Understanding the Two Fuel Pump Systems on Your LaCrosse

Before you start digging into the relay and pump, it helps to know that the 2010 LaCrosse can have more than one fuel pump depending on which engine your car has. This distinction matters when you are troubleshooting a no-start condition:

In-Tank Fuel Pump Module: All 2010 LaCrosse models have a main fuel pump module located inside the fuel tank. This is the primary pump that draws fuel from the tank and sends it to the engine at 40-60 PSI. The in-tank pump is controlled by the fuel pump relay.

High-Pressure Fuel Pump (Direct Injection): If your LaCrosse has the 2.4L four-cylinder engine or the 3.6L V6 with direct injection, there is a second pump mounted on the engine itself. This pump raises fuel pressure to much higher levels for the direct injection system. The high-pressure pump is mechanically driven and does not use the same relay that controls the in-tank pump. If you have starting issues and own a 2.4L model, General Motors issued a special coverage bulletin (TSB 12313) related to the high-pressure fuel pump's plunger shaft seal wearing out, which can cause rough running and a P0172 code.

How to Test the Fuel Pump Relay

Once you have located the relay, testing it takes only a few minutes and requires no special tools beyond a multimeter or a spare relay.

Method 1: The Swap Test

The easiest way to test a relay is to swap it with an identical relay from the same fuse box. Most modern GM vehicles use the same relay for multiple functions. Find another relay in the fuse box that has the same part number printed on top, pull both relays out, and swap their positions. If the car starts or the fuel pump primes when you turn the key, your original relay was bad.

Method 2: Listen for the Fuel Pump

With the relay in place, turn the ignition key to the "on" position without cranking the engine. You should hear a brief whirring or buzzing sound coming from the rear of the car for about two seconds. That sound is the fuel pump priming. If you hear nothing, the relay may not be sending power to the pump, or the pump itself may be faulty.

Method 3: Check for Power at the Relay Socket

If you have a multimeter, you can verify that power is reaching the relay socket. With the key in the "on" position, check for 12 volts at the relay socket terminals. Consult a wiring diagram to identify which pins should be hot, but a simple test for presence of voltage can confirm whether the circuit is live.

Common Symptoms of a Failing Fuel Pump Relay

A bad fuel pump relay does not always fail completely. Sometimes it works intermittently, which makes diagnosis frustrating. Watch for these signs:

  1. Engine cranks but will not start. This is the most common symptom. The starter turns the engine over, but there is no fuel pressure, so the engine never fires.
  2. The car starts sometimes but not others. An intermittent relay may work when cool and fail when hot, making the problem appear random.
  3. No fuel pump priming sound. When you turn the key, you should hear the pump hum from the rear of the car. If you hear nothing, the relay or pump is not getting power.
  4. Engine stalls while driving and then restarts after a few minutes. A failing relay can cut power to the pump suddenly, causing a stall. After the relay cools, it may work again temporarily.
  5. Check Engine Light comes on with specific codes. A fuel pump circuit fault may trigger codes related to low fuel pressure or a circuit malfunction.

How to Replace the Fuel Pump Relay

Replacing the relay is one of the simplest maintenance jobs you can do on a 2010 LaCrosse. Here is the step-by-step process:

  1. Turn off the ignition and remove the key from the ignition cylinder.
  2. Open the hood and locate the fuse box on the driver's side.
  3. Remove the fuse box cover and set it aside.
  4. Locate the fuel pump relay using the diagram on the cover or the owner's manual.
  5. Grasp the relay firmly and pull it straight up. Most relays pull out with moderate force. If it is stuck, gently rock it back and forth while pulling.
  6. Compare the old relay with a new one to confirm the part number matches. For the 2010 LaCrosse, GM part number 13503102 is the multi-use relay used for the fuel pump circuit.
  7. Press the new relay straight down into the socket until it seats firmly.
  8. Replace the fuse box cover and close the hood.
  9. Turn the ignition to the "on" position and listen for the fuel pump prime sound to confirm the new relay works.

When the Relay Is Not the Problem

If you have swapped the relay, checked for power, and confirmed the fuel pump receives voltage but the car still will not start, the problem may lie elsewhere. Several other fuel system components can produce symptoms similar to a bad relay:

  • Faulty fuel pump: The pump motor itself may be worn out or burned out. A failing pump often makes a loud whining sound from the fuel tank before it completely dies.
  • Clogged fuel filter: A severely restricted fuel filter can reduce fuel flow and cause stalling or hesitation, though it will not stop the pump from priming.
  • Failed fuel pump sending unit: If the level sensor inside the tank fails, your gas gauge will read incorrectly, which can mislead you into thinking you have fuel when the tank is empty.
  • Security system interference: Modern cars have immobilizer systems that can prevent starting if they malfunction. If the security light flashes on the dash, this may be the culprit rather than fuel delivery.
  • Crankshaft position sensor: The engine computer uses this sensor to determine when to fire the spark plugs. If it fails, the engine will crank but not run, even with proper fuel pressure.

The Cost of a Replacement Relay

A new fuel pump relay for a 2010 Buick LaCrosse is inexpensive. An OEM GM relay (part number 13503102) typically costs between $10 and $25 at a dealership or online parts retailer. Aftermarket relays from brands like Standard Motor Products or Duralast are even cheaper, usually under $15. There are no special tools required, and the replacement takes about five minutes.

Compare that to the cost of replacing a fuel pump module. A new in-tank fuel pump module assembly for the LaCrosse ranges from roughly $114 for a TRQ brand unit to well over $200 for a Delphi OEM-grade module. Labor adds significant cost because the fuel tank must be dropped to access the pump, making this a four-out-of-five difficulty job. Diagnosing the relay first can save you hundreds of dollars if that is all that is wrong.

Preventative Tips for Fuel System Longevity

To keep your fuel system healthy and reduce the chances of relay or pump failure, follow these practical habits:

  1. Do not drive on a near-empty tank. Running low on fuel regularly can cause the pump to overheat and suck in debris from the bottom of the tank, which shortens its lifespan.
  2. Replace the fuel filter on schedule. Most manufacturers recommend replacing the fuel filter every 15,000 to 30,000 miles, which keeps contaminants from reaching the pump and injectors.
  3. Use quality fuel. High-quality gasoline contains detergents that help keep fuel injectors and the system clean. Avoid using low-quality or stale fuel.
  4. Listen for unusual sounds. If you hear a loud whine or hum from the rear of the car, have the fuel system inspected before the pump fails completely.

Choosing the Right Replacement Fuel Pump: Why KEMSO Delivers

If your diagnostic work confirms that the fuel pump itself needs replacement, you want a part that will last and perform like the original. That is where KEMSO stands out in the aftermarket. KEMSO fuel pumps are built as high-performance, OEM-replacement units designed to match or exceed factory specifications. Each pump is engineered with durable materials and precision construction to deliver consistent fuel pressure under demanding driving conditions, so you get reliable starts and smooth performance mile after mile.

KEMSO stands behind every product with a lifetime warranty, which means your investment is protected for as long as you own your vehicle. Whether you drive a daily commuter or a performance-oriented garage build, KEMSO offers the reliability and peace of mind you want from a replacement fuel pump. With direct-fit designs and rigorous testing standards, KEMSO makes the replacement process straightforward and worry-free. When you need a fuel pump you can trust, choose KEMSO.

Visit https://www.kemsoracing.com/ to browse the full lineup of KEMSO fuel pumps and find the exact fit for your Buick LaCrosse. Their selection covers a wide range of vehicle applications, and each product ships quickly with the warranty and support you expect from a quality parts brand.

Final Thoughts

Finding the fuel pump relay on a 2010 Buick LaCrosse is a simple task once you know where to look. The relay sits in the under-hood fuse box on the driver's side, and testing or replacing it takes less than ten minutes. Start your diagnosis by listening for the fuel pump prime sound, then swap the relay with an identical one to rule it out as the cause. If the relay checks out fine, look deeper into the fuel pump module, the fuel filter, or the security and ignition systems before committing to expensive repairs. A methodical approach will save you time, money, and unnecessary part replacements.

Understanding the layout of your fuel delivery system gives you the confidence to handle basic troubleshooting yourself and makes you a smarter consumer when professional help is necessary. Keep this guide handy, and the next time your LaCrosse refuses to start, you will know exactly where to begin. And for a fuel pump replacement you can trust for the long haul, remember the KEMSO brand and its lifetime warranty commitment at https://www.kemsoracing.com/.


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