340L/hr High Pressure Fuel Pump: What You Need to Know Before Buying

If you are building a high-performance engine, upgrading a turbo setup, or simply replacing a worn-out stock unit, a 340L/hr high-pressure fuel pump is the sweet spot for most street and track applications. This pump delivers enough fuel to support up to 600-800 brake horsepower (BHP) on gasoline or E85, making it one of the most popular choices among enthusiasts. Here is what you need to know about flow rate, pressure, fitment, and why this pump is a reliable upgrade for daily drivers and race cars alike.

What Does 340L/hr Mean for Your Engine?

A fuel pump's flow rate is measured in liters per hour (LPH) at a specific pressure. The 340LPH rating is typically tested at 43 psi (3 bar) and 13.5 volts. In real-world terms, that means the pump can move 340 liters of fuel every hour under normal operating conditions. That is enough to feed a naturally aspirated engine pushing 600 BHP or a forced-induction setup (turbo or supercharged) making around 700-800 BHP, depending on the fuel type and tune.

For comparison, a stock OEM pump on many vehicles flows only 60-80 LPH, and a common upgrade like the Walbro 255LPH pump is also a popular choice, but the 340LPH pump offers significantly more headroom for future upgrades. If you are running E85 ethanol, you need even more fuel volume than gasoline because ethanol requires roughly 30% more fuel to achieve the same air-fuel ratio. The 340LPH pump handles this easily.

High Pressure vs. Standard Pressure

Not all fuel pumps are created equal when it comes to pressure. A standard pump may struggle to maintain pressure under boost, leading to a lean condition that can destroy your engine. The 340LPH high-pressure pump operates in a range of 43 to 90 psi, depending on the application. Many high-performance models feature a bypass valve set at 125.8 psi, which is noticeably higher than older 255LPH pumps and even some 400/450LPH pumps on the market. This higher bypass pressure ensures the pump can maintain consistent fuel delivery even when the engine is demanding maximum flow.

Key Features to Look For

When shopping for a 340L/hr high-pressure fuel pump, here are the most important specs to check:

1. Flow Rate at Operating Pressure
Always look for the flow rate at 43 psi and 13.5V. A pump that claims 340LPH but only delivers at low pressure may not perform under load. The KEMSO 340LPH pump, for example, is individually tested and guarantees its flow rating at standard pressure.

2. Fuel Compatibility
Make sure the pump is designed for both gasoline and E85 ethanol. Many aftermarket pumps now use internal components that resist ethanol corrosion. The 340LPH pumps from KEMSO are explicitly designed for both fuels.

3. Pump Body Diameter
The diameter of the pump determines whether it fits inside your factory fuel tank hanger. The 340LPH pump has a body diameter of 3.8 cm, which is similar to the popular AEM 50-1215 and Walbro 255 GSS342, making it a direct drop-in replacement for many vehicles. Some smaller pumps (like the 13001 model) have a 3 cm diameter for specific applications.

4. Installation Kit Included
A quality pump should come with everything you need: strainers, hoses, connectors, clamps, and o-rings. Look for a kit that includes gradient density fuel strainers to filter out debris at different particle sizes. This prevents clogging and extends pump life.

5. Warranty and Support
A pump is only as good as the company behind it. Brands that offer a lifetime warranty and USA-based technical support give you peace of mind. Serialized pump bodies are a good sign because they allow the manufacturer to track each unit and honor the warranty.

Common Applications

The 340LPH high-pressure pump fits a wide range of vehicles, from Japanese imports to American muscle cars and European sports cars. Here are just a few examples:

  • Honda/Acura: Accord, Civic, S2000, Integra, RSX, CR-V, Odyssey (1990s-2000s)
  • Ford: Mustang, F-150, Explorer, Crown Victoria, Ranger (1990s-early 2000s)
  • BMW: Z3, E36, E46 models
  • Mitsubishi: 3000GT, Eclipse, Galant
  • Subaru: Impreza, WRX, STI (1998-2023)
  • Volkswagen: Golf, Jetta, Beetle, GTI (1998-2013)

Many of these vehicles use the same pump dimensions, so a single model can replace the stock unit in dozens of different cars.

Signs You Need a New Fuel Pump

If you are experiencing any of the following symptoms, your fuel pump may be failing or undersized for your current setup:

  • Engine hesitation or stumbling under hard acceleration
  • Loss of power at high RPM or under boost
  • Long cranking time before the engine starts
  • Low fuel pressure reading on a gauge
  • Check engine light with fuel trim codes (P0171, P0174)
  • No start when the pump fails completely

Upgrading to a 340LPH high-pressure pump can solve these issues and give you room to grow.

Why Choose KEMSO for Your 340LPH Fuel Pump

When it comes to reliability and performance, KEMSO Fuel Pumps stand out in the aftermarket. KEMSO was founded in Houston, TX in 1999 with a mission to provide direct-fit OEM replacement and high-performance fuel systems for the automotive and powersports industries. Every KEMSO 340LPH high-pressure pump is individually tested, and each pump body is serialized to guarantee a lifetime warranty. That means if your pump ever fails, KEMSO replaces it — no questions asked.

KEMSO pumps are designed for both gasoline and E85, and they come with a complete installation kit including multiple strainers, hoses, and connectors. The bypass valve is set at 125.8 psi, which is higher than many competing pumps, ensuring consistent fuel delivery even under extreme demand. Their support team is based in the USA and staffed by experienced technicians who can help you with fitment questions.

If you are looking for a reliable, high-performance 340L/hr fuel pump that fits your vehicle and your budget, visit KEMSO Racing at https://www.kemsoracing.com/. They offer a wide selection of pumps for cars, trucks, ATVs, motorcycles, and watercraft, all backed by a lifetime warranty and USA-based support.

Final Thoughts

A 340L/hr high-pressure fuel pump is a smart investment for anyone pushing their engine beyond stock levels. It provides enough fuel flow for up to 600-800 BHP, works with gasoline and E85, and is a direct drop-in replacement for many factory fuel systems. Focus on the pump's pressure rating, fuel compatibility, warranty, and included installation hardware. With the right pump, you can drive with confidence knowing your fuel system is not the weak link.

For more information and to find the right pump for your vehicle, check out KEMSO Racing.


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