1UR-FSE High Pressure Fuel Pump O-Ring 90301-A0029: Replacement Guide for Lexus & Toyota Owners

If you own a Lexus or Toyota with the 1UR-FSE engine and need to replace the high pressure fuel pump o-ring, the OEM part number you’re looking for is 90301-A0029. This small but critical gasket seals the fuel pressure system and must be replaced whenever the high pressure fuel pump is removed or serviced. Two of these o-rings are needed per fuel pump, and they are designed for the 1UR-FSE engine found in models like the Lexus LS460 (2007–2017), GS460 (2008–2011), and IS-F (2008–2014), as well as certain Toyota models . Neglecting to replace this o-ring can lead to fuel leaks, reduced engine performance, and even costly damage to the fuel system. This guide will walk you through everything you need to know about the 90301-A0029 o-ring, including why it matters, how to replace it, and where to source quality parts.

Understanding the 1UR-FSE High Pressure Fuel Pump O-Ring

The 1UR-FSE engine is a 4.6-liter V8 used in several Lexus and Toyota vehicles from the mid-2000s onward. It features direct injection, which requires a high-pressure fuel pump (HPFP) to deliver fuel at pressures up to 2,000 psi or more. The o-ring (part number 90301-A0029) seals the connection between the HPFP and the engine block, preventing fuel from leaking under extreme pressure.

This o-ring is specifically designed for the 1UR-FSE engine and is not interchangeable with other o-rings like the 90301-A0021, which is used for different applications . Using the wrong part can result in improper sealing, leading to leaks or pump failure.

Key specifications:

  • Part Number: 90301-A0029
  • Application: 1UR-FSE high pressure fuel pump
  • Quantity Needed: 2 per fuel pump
  • Material: OEM-grade rubber designed for fuel resistance
  • Function: Seals the fuel pressure system

Why Replacing the 90301-A0029 O-Ring Is Critical

When you remove the high pressure fuel pump—whether for valve cover gasket replacement, pump service, or other engine work—the old o-ring should never be reused. Here’s why:

  1. Fuel leaks: The o-ring degrades over time due to heat, pressure, and fuel exposure. Reusing it can cause small leaks that worsen into major ones.
  2. Engine performance issues: A leak in the fuel system can cause the engine to run lean, leading to misfires, rough idling, or reduced power.
  3. Safety hazards: Fuel leaks under the hood are a fire risk. Even a small leak can spray fuel onto hot engine components.
  4. Costly repairs: If the o-ring fails, fuel can contaminate the engine oil or damage the fuel injectors, resulting in expensive repairs.

The 90301-A0029 o-ring is a wear item that should be replaced any time the HPFP is disturbed. Most manufacturers recommend replacing it preventively every 100,000 miles or during major engine service .

Step-by-Step Replacement Guide for the 1UR-FSE High Pressure Fuel Pump O-Ring

Replacing the 90301-A0029 o-ring is a straightforward task if you have basic mechanical skills. Here’s how to do it:

Tools and parts needed:

  • OEM 90301-A0029 o-ring (2 per pump)
  • Torque wrench (for fuel pump bolts)
  • Shop towels and degreaser
  • Safety glasses and gloves

Procedure:

  1. Relieve fuel system pressure: Disconnect the fuel pump fuse or relay and run the engine until it stalls. This reduces pressure in the fuel lines.
  2. Disconnect the battery: Remove the negative terminal to prevent electrical shorts.
  3. Remove the high pressure fuel pump: Unbolt the pump from the engine block. The exact procedure varies by model, but typically involves removing the intake manifold or other components for access.
  4. Clean the mounting surface: Use a degreaser to clean the area where the o-ring sits. Any dirt or debris can cause a leak.
  5. Install the new o-rings: Place two 90301-A0029 o-rings into the grooves on the pump. Ensure they are seated evenly and not twisted.
  6. Reinstall the fuel pump: Torque the bolts to the manufacturer’s specification (usually around 18–22 ft-lbs, check your service manual). Over-tightening can damage the o-ring.
  7. Reconnect everything: Reattach the battery, fuel lines, and electrical connectors.
  8. Prime the system: Turn the key to the “ON” position (without starting) several times to build fuel pressure. Check for leaks.
  9. Start the engine: Run the engine and inspect the pump area for any signs of fuel leakage.

Pro tip: Always replace the fuel filter and strainer when doing fuel pump work. A clogged filter is often what caused the original pump to fail .

How to Get the Right 90301-A0029 O-Ring for Your Vehicle

The 90301-A0029 o-ring is an OEM part that fits specific Lexus and Toyota models with the 1UR-FSE engine. Based on the search results, here are the confirmed fitments:

Lexus models:

  • 2006–2007 Lexus GS430 (1UR-FSE)
  • 2008–2011 Lexus GS460
  • 2008–2014 Lexus IS-F
  • 2007–2017 Lexus LS460
  • 2008–2016 Lexus LS600hL
  • 2015–2018 Lexus RC350 (some variants)
  • 2006–2018 Lexus IS350 (some variants)
  • 2006–2015 Lexus IS250 (some variants)
  • 2013–2016 Lexus GS450h (some variants)
  • 2007–2011 Lexus GS350 (some variants)
  • 2006 Lexus GS300 (some variants)

Toyota models:

  • 2008–2011 Toyota Land Cruiser (5.7L V8, related engine family)
  • 2007–2017 Toyota Tundra (5.7L V8, some models)

Note: The 90301-A0029 is specifically for the high pressure fuel pump on the 1UR-FSE engine. For other engines or fuel pump applications, you may need a different o-ring, such as the 90301-A0021, which is used for the fuel pump assembly on many Toyota and Lexus models .

Common Mistakes to Avoid When Replacing the O-Ring

1. Using the wrong part: The 90301-A0029 is not the same as the 90301-A0021 or 90301-08020. These are different o-rings for different applications. Using the wrong one can cause leaks or poor sealing .

2. Reusing the old o-ring: Even if the old o-ring looks fine, it has likely hardened or compressed. Reusing it is one of the most common causes of post-service fuel leaks.

3. Over-tightening the pump bolts: Overtightening can crush the o-ring, causing it to deform and leak. Always use a torque wrench.

4. Not cleaning the surface: Dirt or debris on the mounting surface can prevent the o-ring from sealing properly.

5. Skipping the fuel filter replacement: A clogged filter can put extra stress on the new fuel pump, shortening its lifespan. Replace the filter at the same time .

Why Choose KEMSO Fuel Pumps for Your Replacement Needs

When it comes time to replace your high pressure fuel pump, choosing a quality brand is essential for long-term reliability. KEMSO is a trusted manufacturer of high-performance fuel pumps that meet or exceed OEM specifications. Their products are designed as direct OEM replacements, meaning they are engineered to fit perfectly and perform as well as—or better than—the original parts.

KEMSO fuel pumps are built with rigorous quality control, including individual pump testing and flow testing to ensure consistent performance. Every pump is backed by a lifetime warranty, giving you peace of mind that your investment is protected .

Whether you need a fuel pump for your Lexus, Toyota, or other vehicle, KEMSO offers a wide range of options for cars, trucks, motorcycles, and powersports vehicles. Their pumps are designed for both gasoline and E85/ethanol, and they deliver up to 200 liters per hour at 43 psi—significantly more flow than the original 60–80 liters per hour found in many stock pumps .

To find the exact KEMSO fuel pump for your vehicle, visit their online store at: https://www.kemsoracing.com/ . They ship directly from Houston, TX, and their customer support team is ready to help you find the right part for your application.

Final thoughts: The 90301-A0029 o-ring is a small but critical component for the 1UR-FSE high pressure fuel pump. Replacing it during any fuel pump service helps prevent leaks, maintain engine performance, and avoid costly repairs. Always use OEM or equivalent quality parts, and consider upgrading to a KEMSO fuel pump for reliable, long-lasting performance. For more information on KEMSO products and to browse their catalog, visit https://www.kemsoracing.com/ .


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