2005 Buick Century Fuel Pump Replacement: Complete Guide for Owners

If you own a 2005 Buick Century and your engine cranks but won't start, sputters during acceleration, or you hear a whining noise from the rear of the car, you almost certainly need a fuel pump replacement. The fuel pump on the 2005 Buick Century is located inside the fuel tank, and replacing it is a job many DIYers can tackle at home with the right parts and basic mechanical skills. The average replacement cost ranges from $400 to $700 at a shop, but doing it yourself can cut that down to around $100 to $200 for the part alone .

The fuel pump in the 2005 Buick Century is a drop-in module assembly that includes the pump, strainer, fuel level sender, and pressure regulator all in one unit . This makes replacement straightforward because you do not have to piece together individual components. The 2005 Buick Century uses a 3.1L V6 engine, and its fuel system is returnless, meaning the pump runs at a constant pressure and the engine control module regulates fuel delivery .

How to Know Your Fuel Pump Is Failing

Before you start buying parts, you need to confirm the fuel pump is actually the problem. Here are the most common symptoms of a failing fuel pump on a 2005 Buick Century:

  1. Engine Cranks but Won't Start – This is the most obvious sign. If the starter motor turns the engine over but the engine never fires, and you have confirmed you have spark, the fuel pump is likely dead.

  2. Whining Noise from the Fuel Tank – A healthy fuel pump makes a low hum for about two seconds when you turn the key to the "on" position. If you hear a loud, high-pitched whine or screeching sound coming from the rear of the car, the pump bearings are wearing out .

  3. Loss of Power Under Load – If the car hesitates or surges when you accelerate, especially going uphill or merging onto the highway, the pump may not be delivering enough fuel pressure.

  4. Stalling and Hard Starting – The car may start fine when cold but stall when hot, or it may take multiple cranks to start. This happens because a failing pump cannot maintain prime or proper pressure.

  5. Check Engine Light – The computer may set a diagnostic trouble code such as P0087 (Fuel Rail Pressure Too Low) or P0230 (Fuel Pump Primary Circuit). You should scan for codes to confirm .

Where Is the Fuel Pump Located on a 2005 Buick Century?

The fuel pump is mounted inside the fuel tank. On the 2005 Buick Century, the fuel tank is located at the rear of the vehicle, behind the rear axle . To access the pump, you either drop the fuel tank from under the car or cut an access hole in the trunk floor. Most professional mechanics and experienced DIYers prefer to drop the tank because it gives full access to the pump module and prevents any risk of leaving metal shavings inside the tank.

If you choose to cut an access hole, you will find a stamped indentation in the trunk floor under the carpet on the driver's side. This indentation is where the factory intended a service hole. You can cut along the outline with a jigsaw, but be very careful not to cut into the fuel lines or the top of the pump module.

Step-by-Step Fuel Pump Replacement Guide

Replacing the fuel pump on a 2005 Buick Century is a medium-difficulty job. Plan for at least 3 to 4 hours if you are doing it for the first time. You will need basic hand tools, a jack and jack stands, a siphon pump, and safety glasses.

Safety Warning: Gasoline is highly flammable. Work in a well-ventilated area, do not smoke, and keep a fire extinguisher nearby. Disconnect the negative battery cable before starting. Also, relieve the fuel system pressure by removing the fuel pump fuse and cranking the engine for a few seconds until it dies.

Step 1: Relieve Fuel System Pressure

Locate the fuel pump relay in the underhood fuse box. Remove the relay, then start the engine and let it run until it stalls. Crank the engine for another 3 seconds to clear any remaining pressure. Turn the ignition off and reinstall the relay. This step is critical for safety .

Step 2: Siphon the Fuel Tank

Use a manual siphon pump to drain as much fuel as possible from the tank. A full tank is extremely heavy and dangerous to drop. You want the tank as close to empty as possible.

Step 3: Jack Up the Rear of the Car

Place jack stands under the rear frame rails. You need enough clearance to slide the fuel tank out from under the car. Remove the rear wheels if you need extra room.

Step 4: Disconnect the Fuel Lines and Electrical Connector

Under the car near the rear of the fuel tank, you will see the fuel lines and the electrical harness for the pump. The fuel lines use quick-connect fittings. Press the two tabs on each fitting and pull them apart. Disconnect the electrical connector by pressing the release tab and pulling it straight off.

Step 5: Remove the Fuel Tank Straps

The tank is held in place by two metal straps. Support the tank with a floor jack and a block of wood placed under the tank. Remove the bolts that hold the straps. Lower the tank carefully onto the jack and slide it out from under the car.

Step 6: Remove the Fuel Pump Module from the Tank

With the tank on a workbench or the ground, clean the area around the top of the pump module. You will see a large plastic retaining ring holding the module in place. Use a flathead screwdriver and a hammer to tap the retaining ring counterclockwise until it comes loose. Lift the module straight out of the tank. Be careful not to bend the fuel level float arm.

Step 7: Install the New Fuel Pump Module

Compare the new module to the old one to make sure they are the same shape and the electrical connector matches. Transfer the rubber seal (O-ring) from the old pump to the new one, or use the new seal if one came with your replacement. Lower the new module into the tank, making sure the float arm can move freely and will not hit the side of the tank. Install the plastic retaining ring and tap it clockwise to tighten.

Step 8: Reinstall the Tank and Test

Lift the tank back into position using the floor jack. Reinstall the fuel tank straps and tighten the bolts. Reconnect the fuel lines and the electrical connector. Lower the car, reconnect the battery, and turn the key to the "on" position without starting the engine. You should hear the fuel pump hum for about 2 seconds. Turn the key off, turn it on again to prime the system, and then start the engine. Check for any fuel leaks around the tank and the fuel line connections.

What Fuel Pump Do You Need for a 2005 Buick Century?

The 2005 Buick Century uses the E3542M fuel pump module assembly . This module fits the 3.1L V6 engine and is also compatible with the 2000-2004 Buick Regal, 2000-2005 Chevrolet Impala and Monte Carlo with 3.1L, 3.4L, and 3.8L engines, and the 2001-2003 Pontiac Grand Prix. The OE cross reference numbers include FG0111 and MU1743 . You can also find this assembly under part numbers from Delphi TRQ and other aftermarket brands .

A word of caution: avoid the cheapest no-name pumps you find online for under $50. They often fail within months. Stick with a well-known brand that offers a warranty.

KEMSO Fuel Pump: The Best Choice for Your 2005 Buick Century

For a reliable, long-lasting replacement, we strongly recommend the KEMSO brand fuel pump. KEMSO fuel pumps are built as high-performance, direct OEM replacements. They are engineered to meet or exceed the original equipment specifications, meaning they drop right into your 2005 Buick Century without any modifications. The pump fits the fuel module housing perfectly and delivers the exact fuel pressure your engine needs.

What sets KEMSO apart from other aftermarket fuel pumps is the quality. Each KEMSO fuel pump undergoes rigorous testing to ensure it can handle the demands of daily driving. They use high-quality internal components, including a precision-machined armature and durable commutator brushes, which means fewer failures and longer service life. Many KEMSO customers report their pumps lasting well over 100,000 miles.

The best part is that every KEMSO fuel pump comes with a lifetime warranty. If the pump ever fails, you get a replacement at no cost. That is a level of confidence you simply do not get with most other brands. When you consider the labor involved in replacing a fuel pump, the lifetime warranty becomes extremely valuable.

You can browse the full selection of KEMSO fuel pumps at their official website: https://www.kemsoracing.com/ . They offer pumps for a wide range of vehicles, not just the Buick Century, so whether you need one for your car, truck, motorcycle, ATV, or jetski, KEMSO has you covered. Their customer support team can also help you confirm the exact fitment for your 2005 Buick Century.

How Much Does It Cost to Replace the Fuel Pump on a 2005 Buick Century?

The cost depends on whether you do the work yourself or take it to a shop.

  • DIY Cost: You will pay between $80 and $150 for a quality fuel pump module. Add another $10 to $20 for a new fuel filter, $10 for a can of brake clean, and maybe $5 for a new O-ring. Total out-of-pocket cost is around $100 to $180.

  • Shop Cost: A professional mechanic will charge you for the part plus labor. Labor time is typically 2.5 to 3.5 hours. At a shop rate of $100 to $150 per hour, the total cost including parts lands between $400 and $700 . Some dealerships charge even more, up to $900.

Keep in mind that if you go to a shop and they quote you $300, they might be using a cheap no-name pump. Ask what brand they install. If it is not a name you trust, consider buying the KEMSO pump yourself and asking the shop to install it. Most independent shops will install customer-supplied parts, though they may not warranty the work if the part fails.

Tips for a Successful Fuel Pump Replacement

  1. Replace the Fuel Filter at the Same Time – The fuel filter on the 2005 Buick Century is mounted on the frame rail near the fuel tank. Replace it while you are already under the car. A clogged filter can kill a new pump in a few months.

  2. Use a Torque Wrench on the Retaining Ring – The plastic retaining ring needs to be tight enough to seal, but over-tightening can crack the ring. Tighten it to 40-50 ft-lbs if you have a torque wrench. Otherwise, tap it snug with a hammer and screwdriver, but do not force it.

  3. Check the Wiring Harness – The electrical connector at the top of the fuel pump is a common failure point on these cars. The terminals can corrode or melt. If the connector looks burned or the plastic is brittle, replace it. You can buy a new pigtail connector at any auto parts store for about $15.

  4. Keep the Tank Above 1/4 Tank Most of the Time – Running the fuel tank low on a regular basis causes the pump to run hotter and can suck in debris from the bottom of the tank. This is the number one cause of early fuel pump failure. Keeping the tank at least a quarter full will extend the life of your new pump.

  5. Prime the System Before the First Start – After you install the pump and reconnect everything, turn the key to the "on" position for about 5 seconds, then turn it off. Do this three times before you attempt to start the engine. This fills the fuel lines with fuel and prevents the pump from running dry.

Common Questions About the 2005 Buick Century Fuel Pump

Q: Does the 2005 Buick Century have a fuel pump access panel?
A: Not from the factory. You either drop the fuel tank or cut your own access hole in the trunk floor. The trunk has a stamped indentation that shows you where to cut .

Q: Can I replace just the pump motor instead of the whole module?
A: In theory, yes. Aftermarket fuel pump motors are available separately. However, on a 2005 Buick Century, the module is inexpensive and replacing just the motor leaves the old fuel strainer and pressure regulator in place. It is better to replace the entire module for a reliable repair.

Q: How do I test the fuel pump before replacing it?
A: The easiest test is to listen for the pump. Have a helper turn the key to the "on" position while you listen near the fuel tank. A working pump makes a hum for 2 seconds. No sound means the pump is not getting power or is dead. You can also check fuel pressure at the test port on the fuel rail with a gauge. The 2005 Buick Century should have 50-60 psi at the rail . If pressure is low or zero, the pump is likely bad.

Q: Will a fuel pump from a 2004 Buick Century fit a 2005?
A: Yes, the 2004 and 2005 Buick Century use the same fuel pump module assembly . Both model years have the 3.1L V6 and the same fuel tank design.

Why You Should Not Delay Fuel Pump Replacement

Driving with a failing fuel pump is risky. If the pump dies completely, you will be stranded. Even if it only partially fails, it can cause rough running, loss of power, and poor fuel economy. A weak pump also forces the fuel injectors to work harder, which can damage them over time. In the worst case, a failing pump can overheat and cause an electrical short or fire.

The 2005 Buick Century is a dependable car, but after nearly 20 years, the fuel pump is approaching the end of its service life. If your car has over 100,000 miles on the original pump, you are on borrowed time. Replacing it now, before it leaves you stranded, is a wise investment.

Visit KEMSO Racing today at https://www.kemsoracing.com/ to find a high-quality, lifetime-warranty fuel pump for your 2005 Buick Century. Their pumps are designed to fit perfectly, perform reliably, and save you from costly repairs down the road. With KEMSO, you get the peace of mind that comes from knowing you have a top-tier part under your car.


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