340LPH Inline Fuel Pump: The Ultimate Upgrade for High Performance Engines

If you are building a high horsepower engine or simply replacing a worn-out factory fuel pump, a 340LPH inline fuel pump is the most reliable and cost-effective solution on the market today. A 340LPH (liters per hour) pump delivers enough fuel flow to support engines producing up to 1,100 horsepower, making it the go-to choice for turbocharged, supercharged, and naturally aspirated builds alike . Unlike many smaller pumps that struggle to maintain pressure under boost, a quality 340LPH pump maintains high flow rates even at elevated fuel pressures, ensuring your engine gets the fuel it needs under all conditions . The key takeaway is simple: upgrading to a 340LPH inline fuel pump is one of the smartest investments you can make for performance, reliability, and peace of mind.

What Is a 340LPH Inline Fuel Pump?

A 340LPH inline fuel pump is a high-flow, high-pressure electric pump designed to be mounted externally or inside the fuel tank. It moves 340 liters of fuel per hour when tested at 43 PSI and 13.5 volts, which is a standard benchmark in the industry . This flow rate is significantly higher than the common 255LPH pumps, making the 340LPH a popular upgrade for enthusiasts who need more fuel without switching to a larger or more expensive pump .

These pumps are widely used in both daily drivers and dedicated race cars. They are compatible with gasoline, E85, and even methanol fuels, giving you the flexibility to run alternative fuels without worrying about pump failure . The inline design means you can mount the pump anywhere along the fuel line, which simplifies installation in custom builds where in-tank space is limited.

How Much Power Can a 340LPH Pump Support?

The power capacity of a 340LPH pump depends on the fuel type and the boost pressure you are running. On gasoline, a quality 340LPH inline pump can support over 1,100 horsepower at the flywheel . When running E85, which requires approximately 30% more fuel volume, the same pump can still support around 700 to 800 horsepower, which is more than enough for most street and track applications .

Here is a quick breakdown of what you can expect:

1. Gasoline engines: 700 to 1,100+ horsepower, depending on boost pressure and fuel system design.
2. E85 and ethanol blends: 700 to 800 horsepower, making it a solid choice for flex-fuel vehicles.
3. High boost applications: The pump maintains excellent flow at higher pressures. For example, the Clean Injection 340LPH pump flows 300 LPH at 75 PSI and 240 LPH at 120 PSI, which is critical for forced induction setups .

Key Features to Look for in a 340LPH Inline Fuel Pump

Not all 340LPH pumps are created equal. When shopping for a pump, pay attention to the following features to ensure you get a reliable product that will last.

1. Direct OEM Replacement Compatibility

Many 340LPH pumps are designed as direct drop-in replacements for factory fuel pumps. The KEMSO 340LPH pump, for example, has similar dimensions to the popular Walbro 255 GSS342, meaning it fits into the same mounting points without modification . This makes upgrading a simple plug-and-play process.

2. E85 and Alcohol Compatibility

If you plan to run ethanol or methanol, make sure the pump is explicitly rated for those fuels. Most reputable 340LPH pumps, including those from KEMSO and Clean Injection, are E85 compatible, though running alcohol may reduce the pump's lifespan . The internal materials and turbine design play a big role in long-term durability with corrosive fuels.

3. Flow at High Pressure

A pump's advertised flow rate at 43 PSI is only part of the story. A good 340LPH pump should still deliver strong flow at 70, 90, or even 120 PSI. Look for pumps that provide complete flow curves, like the Clean Injection Pro Series, which publishes flow data from 35 to 120 PSI . This transparency is a sign of a quality manufacturer.

4. Inlet and Outlet Fittings

Inline pumps typically come with AN fittings for easy installation. A common configuration is a -10AN inlet and a -8AN outlet, which matches the standard on Bosch 044-style pumps . These fittings allow you to use braided stainless steel lines and AN fittings throughout your fuel system, reducing the risk of leaks.

5. Mounting Bracket and Vibration Dampening

A good pump kit includes a mounting bracket with a rubber insert to reduce vibration and noise . Vibration can cause premature wear on the pump internals, so a quality mounting solution is essential for long-term reliability.

Installation Tips for a 340LPH Inline Fuel Pump

Installing an inline fuel pump is a straightforward job, but there are a few best practices to follow.

1. Mount the pump as low as possible. Fuel pumps are better at pushing fuel than pulling it. Mount the pump close to the fuel tank and below the fuel level if possible. This helps with priming and prevents cavitation.

2. Use a pre-filter. Always install a fuel filter between the tank and the pump. Even a small piece of debris can damage the pump's internal turbine. Most pump kits include a strainer, but a dedicated inline filter is a good addition .

3. Wire it properly. A 340LPH pump draws significant current. Use a relay and a dedicated power wire from the battery. The pump's positive terminal should be connected through a relay triggered by the engine's fuel pump circuit. This ensures the pump only runs when the engine is on.

4. Secure all connections. Use crimp connectors and heat shrink or properly soldered joints. A loose connection can cause voltage drop, which reduces pump performance and can lead to overheating.

Why Choose a KEMSO 340LPH Fuel Pump?

When it comes to reliability, performance, and value, KEMSO stands out as a top choice for anyone in the market for a 340LPH inline fuel pump. KEMSO fuel pumps are engineered for high-performance applications, whether you are building a daily driver, a fast road car, or a dedicated track machine . Each KEMSO 340LPH pump is individually tested to ensure it meets the rated flow of 340 liters per hour at 43 PSI, so you know exactly what you are getting .

KEMSO pumps are designed as direct OEM replacements, meaning they fit into the factory mounting position without any modifications . This makes them an ideal choice if you are replacing a faulty stock pump and want a significant upgrade in flow capacity. The pump body diameter is 3.8cm, which is very similar to the popular Walbro 255 GSS342, so it fits in most factory hangers .

One of the biggest advantages of choosing KEMSO is the lifetime warranty. KEMSO backs every pump with a promise of quality and confidence, giving you peace of mind that your investment is protected. The company also follows strict quality control programs, including ISO/TSO standards, and each pump undergoes individual flow testing before it leaves the factory . This level of quality assurance is rare in the aftermarket fuel pump industry.

KEMSO offers a wide range of fuel pumps for various vehicles, including cars, motorcycles, ATVs, and watercraft. Whether you need a pump for a Nissan 300ZX, a Subaru Impreza, a Honda Civic, or a Kawasaki Jet Ski, KEMSO has a solution that fits . You can browse their full selection and find the perfect pump for your vehicle at https://www.kemsoracing.com/.

Conclusion

A 340LPH inline fuel pump is a smart, practical upgrade for anyone looking to increase engine performance or replace a failing factory pump. With the ability to support over 1,000 horsepower on gasoline and 700+ horsepower on E85, these pumps offer exceptional value and reliability. When choosing a pump, prioritize features like E85 compatibility, high-pressure flow performance, and a robust mounting system. And if you want a pump that comes with a lifetime warranty, individual testing, and a reputation for quality, look no further than KEMSO. Check out their full lineup at https://www.kemsoracing.com/ to find the right fuel pump for your build.