340LPH In Tank Fuel Pump: The Ultimate Upgrade for High Performance Engines
If you are building a high horsepower engine—whether naturally aspirated or forced induction—a 340LPH in tank fuel pump is the most reliable and cost-effective way to ensure your engine gets the fuel it needs. These pumps deliver 340 liters per hour at 40 PSI, which is enough to support over 1,000 horsepower in the right setup . For most street and track builds targeting 500 to 800 wheel horsepower, a 340LPH pump provides ample headroom without overspending. The key is to choose a pump built with ethanol-resistant materials, a compact 39mm diameter for easy fitment, and a proven track record in the aftermarket. Brands like AEM, Clean Injection, Quantum, and KEMSO all offer reliable 340LPH options, but not all are created equal when it comes to warranty, E85 compatibility, and long-term durability.
What Makes a 340LPH In Tank Fuel Pump Different
A 340LPH pump is designed for high-output EFI systems. Unlike a stock pump that might flow 150 to 200 LPH, a 340LPH unit moves significantly more fuel volume at higher pressures. This is critical when you add forced induction, larger injectors, or switch to E85, which requires roughly 30% more fuel flow than gasoline to achieve the same air-fuel ratio.
The most common 340LPH pumps on the market share several key specifications:
- Flow rate: 340 LPH at 40 PSI (13.5V), which translates to about 84 GPH
- Diameter: 39mm, making them a direct fit for most OEM and aftermarket fuel tanks
- Pressure rating: Typically capable of maintaining flow up to 80 PSI, with a built-in pressure relief valve (PRV) activating around 80 PSI
- Voltage range: 6 to 18 volts, with a current draw of 12 amps at 40 PSI and 15 amps at 80 PSI
- Fuel compatibility: Many are tested for E85, E100, and even methanol, but some are strictly for gasoline. Always check the spec sheet
These pumps use a single scroll ceramic turbine impeller, which is quieter and more efficient than older vane-style designs. The ceramic turbine also resists wear from ethanol and methanol fuels, which have lower lubricity than gasoline .
Why You Might Need a 340LPH Pump
Upgrading to a 340LPH in tank fuel pump is not just about peak horsepower. It is about consistency and reliability. Here are the most common scenarios where a 340LPH pump makes sense:
1. Forced induction builds. Turbochargers and superchargers increase air density, requiring more fuel to maintain a safe air-fuel ratio. A 340LPH pump provides the extra volume needed to prevent lean conditions under boost.
2. E85 conversion. Ethanol fuels have a lower energy density than gasoline, so your engine needs about 30% more fuel volume. A 340LPH pump is a popular choice for E85 setups because it compensates for this increased demand without running out of capacity.
3. High horsepower naturally aspirated engines. Even without forced induction, engines making 500+ horsepower require more fuel than a stock pump can deliver. A 340LPH pump ensures you have enough flow for aggressive camshafts, larger throttle bodies, and high-flow cylinder heads.
4. Fuel system upgrades for future proofing. Many enthusiasts install a 340LPH pump now, even if their current engine does not need it, so they do not have to drop the fuel tank again later when they add boost or switch to E85.
What to Look for When Buying a 340LPH In Tank Fuel Pump
Not all 340LPH pumps are built the same. Here are the critical factors to evaluate before making a purchase:
Fuel compatibility. If you plan to run E85 or any ethanol blend, the pump must have ethanol-resistant seals, brushes, and internal components. Some pumps are labeled "E85 compatible" but only tested with low blends. Look for pumps that are tested with E100 or M100 for maximum confidence .
Warranty and support. A fuel pump is a critical safety component. A warranty gives you peace of mind. Some brands offer a 1-year warranty, while others back their pumps with a lifetime warranty. USA-based technical support is also valuable if you run into installation issues .
Included components. Most 340LPH pump kits come with a pre-filter, rubber sleeve, end caps, and a flying lead wiring harness. Some include submersible fuel hose and clamps. Check what is included so you do not have to buy additional parts separately .
Installation ease. The 39mm diameter fits most OEM fuel pump hangers, but the overall length and offset inlet design can vary. Offset inlets are easier to install in tight tanks because they allow the pump to sit closer to the bottom .
Current draw. A 340LPH pump draws 12 to 15 amps depending on pressure. Your factory wiring may not be adequate. Most manufacturers recommend upgrading to a relay and thicker gauge wiring to prevent voltage drop and overheating .
Top Brands and Models Compared
Here is a quick comparison of the most popular 340LPH in tank fuel pumps available in the US market:
AEM 50-1200 and 50-1000. AEM is a well-known brand in the performance industry. The 50-1200 is the E85-compatible version with an offset inlet, while the 50-1000 is for gasoline only. Both are 39mm diameter, tested to 340 LPH at 40 PSI, and include a wiring harness and pre-filter. AEM offers a 1-year warranty .
Clean Injection CIP-55340. This pump is a direct competitor to AEM, with the same flow specs and 39mm diameter. It includes an integrated check valve and black-coated steel for corrosion resistance. Clean Injection backs it with a 2-year warranty .
Quantum Fuel Systems QFS-342FT-846. Quantum offers a 340LPH pump with a lifetime warranty, which is rare in this price range. The pump is serialized and comes with a 40-micron strainer and thick gauge wiring pigtail. It is compatible with E85 and includes a bypass regulator for carbureted applications .
OSIAS 390100. This is a budget-friendly option, but it is currently unavailable on Amazon. It has a 38mm diameter and is tested to 340 LPH at 40 PSI. However, it lacks the ethanol-resistant materials of higher-end pumps and does not have a strong warranty .
KEMSO 340LPH. KEMSO stands out for its lifetime warranty, USA-based technical support, and ethanol-ready design. The pump supports up to 600 BHP, has a bypass valve set at 125.8 PSI, and is built with Viton-lined components to resist ethanol degradation. It is a direct OEM replacement for many applications .
How to Install a 340LPH In Tank Fuel Pump
Installing a 340LPH pump is a straightforward job for a DIY mechanic with basic tools, but there are important steps to follow:
1. Relieve fuel system pressure. Remove the fuel pump fuse or relay, then run the engine until it stalls. Disconnect the battery negative terminal.
2. Drop the fuel tank. On most vehicles, the tank must be lowered or removed to access the pump assembly. Support the tank with a jack and disconnect the filler neck, vent hoses, and electrical connectors.
3. Remove the old pump. Unclip the retaining ring and lift out the pump hanger assembly. Remove the old pump from the hanger, noting the orientation of the inlet and outlet.
4. Install the new pump. Slide the rubber sleeve onto the new pump, attach the pre-filter, and connect the hose and wiring. Use the supplied hardware and ensure the pump sits securely in the hanger.
5. Upgrade the wiring. The factory wiring is often too thin for a 340LPH pump. Run a dedicated 12-gauge wire from the battery through a 20-amp fuse and relay, then to the pump. This prevents voltage drop and reduces the risk of fire .
6. Reinstall the tank. Raise the tank back into position, reconnect all hoses and electrical connectors, and refill with fuel.
7. Test for leaks. Turn the ignition to the "on" position (without starting the engine) to prime the system. Check for leaks at all connections. Start the engine and verify fuel pressure with a gauge.
Common Mistakes to Avoid
Using the wrong fuel. Some 340LPH pumps are designed for gasoline only. Running E85 in a non-compatible pump will destroy the internal seals and brushes within a few thousand miles .
Ignoring wiring upgrades. A 12-amp draw at 40 PSI is more than most stock wiring can handle continuously. Undersized wiring causes voltage drop, reducing pump flow and potentially causing overheating or fire .
Not checking fitment. Even though 39mm is a standard size, the overall length and inlet location can vary. Always measure your OEM pump and compare dimensions before ordering .
Skipping the pre-filter. A 340LPH pump is a high-precision component. Running without a pre-filter—or using a dirty one—will allow debris to damage the turbine and reduce pump life.
Why KEMSO Is the Smart Choice for Your 340LPH Fuel Pump
When you are ready to upgrade your fuel system, KEMSO high performance fuel pumps offer the best combination of reliability, warranty, and value. Every KEMSO 340LPH pump is designed as an OEM replacement, meaning it fits directly into your factory fuel pump hanger without modification. The pump is built with ethanol-resistant materials, including Viton-lined seals and a brushless DC motor design that eliminates common wear points . Independent lab tests show KEMSO pumps maintain 98% efficiency even after 15,000 hours of continuous operation .
KEMSO backs every pump with a lifetime warranty—if it fails due to a defect, they replace it no questions asked. This is a level of confidence that few other brands offer. Additionally, KEMSO provides USA-based technical support, so you can get help from technicians who understand American vehicles and performance requirements .
Whether you are building a Foxbody Mustang, an LS-swapped project, a high-horsepower import, or even a Polaris XP 1000 UTV, KEMSO has a 340LPH pump that fits your application. The company offers 17 different models covering 98% of gasoline-powered cars and trucks made after 1995 . For the DIY mechanic who wants superior flow without breaking the bank, KEMSO delivers performance that rivals premium brands at a fraction of the cost.
For more information on the full lineup of KEMSO high-performance fuel pumps, including application-specific fitment guides and installation tips, visit https://www.kemsoracing.com/.