AEM 340LPH Fuel Pump: The Ultimate High-Flow Upgrade for Your Performance Build
f you are building a high-performance engine that produces over 500 horsepower, the AEM 340LPH fuel pump is one of the most reliable and widely tested upgrades you can make to your fuel system. This pump delivers 340 liters per hour at 40 PSI, supports up to 1,000 horsepower with proper fuel line sizing, and is fully compatible with E85, methanol, and all types of gasoline. It fits most factory fuel pump housings with little to no modification, and it comes with everything you need for a straightforward installation. Whether you are running a turbocharged build, a supercharged street car, or a high-revving naturally aspirated engine, the AEM 340LPH pump ensures your engine never runs lean under load.
What Makes the AEM 340LPH Fuel Pump Different?
The AEM 340LPH high-flow in-tank fuel pump is not just another aftermarket pump. It is engineered with robust internal construction designed to withstand the low lubricity characteristics of ethanol and methanol fuels. This pump is tested to work with ethanol fuels up to E100, methanol fuels up to M100, and all types of gasoline. Every pump is individually flow tested before it leaves the factory to ensure it delivers the rated 340 liters per hour at 40 PSI. The compact body measures just 39mm in diameter and 65mm in length, making it a direct fit for most factory pump hangers and sending units.
Key specifications include:
- Flow rate: 340 liters per hour at 40 PSI (13.5 volts)
- Operating pressure: 40 to 70 PSI, with a PRV activation at 80 PSI
- Current draw: 12 amps at 40 PSI, 15 amps at 80 PSI
- Fuse requirement: 15 to 20 amps depending on system pressure
- Connector terminal: 6mm spade (positive and negative)
- Voltage range: 6 to 18 volts
- Impeller design: Single scroll ceramic turbine for quiet, efficient operation
- External materials: Black plated steel with laser etching and green end caps
The offset inlet design eases installation in tight spaces, and the pump includes a pre-filter, internal fuel hose, clamps, flying lead, end cap, and rubber buffer sleeve. This is a complete kit that requires no additional parts for most installations.
Flow and Horsepower Support
The AEM 340LPH pump is rated to support up to 1,000 horsepower at 43 PSI when paired with the correct fuel hose diameter. However, flow capability for horsepower support depends on several factors including fuel hose diameter, system electrical voltage, and the engine's brake specific fuel consumption (BSFC). AEM provides a helpful guideline for hose sizing:
- Up to 499 HP: 0.344-inch hose (6AN)
- 500 to 799 HP: 0.437-inch hose (8AN)
- 900 to 1,100 HP: 0.562-inch hose (10AN)
The return hose should be one size smaller than the delivery hose. For typical passenger car applications, using a 0.437-inch (8AN) delivery hose and a 0.344-inch (6AN) return hose covers most performance builds. If you have a long hose run, you should measure actual flow by running the pump into a graduated cylinder and calculating gallons per hour.
The pump's flow curve is linear and predictable. At 13.5 volts and 43 PSI, the pump draws approximately 12 amps and delivers its rated 340 LPH. At higher pressures up to 80 PSI, current draw increases to 15 amps, and flow decreases slightly. This makes the pump suitable for both return-style and returnless fuel systems, as long as the pressure stays within the 40 to 70 PSI operating range.
E85 and Ethanol Compatibility
One of the biggest advantages of the AEM 340LPH pump is its full compatibility with high-ethanol fuels. Many standard fuel pumps fail when exposed to E85 because ethanol is corrosive and has lower lubricity than gasoline. AEM uses internal materials that resist ethanol damage, including ceramic turbine technology and corrosion-resistant coatings. The pump is tested and proven with ethanol blends up to E100 and methanol blends up to M100.
If you are converting your vehicle to E85, this pump is an excellent choice because ethanol requires approximately 30 to 40 percent more fuel volume compared to gasoline to achieve the same air-fuel ratio. The 340 LPH flow rate provides ample headroom for E85 conversions on engines producing 500 to 700 horsepower. For higher horsepower E85 builds, you may need dual pumps or a larger single pump, but for most street and track applications, the AEM 340LPH is sufficient.
Installation Considerations
Installing an AEM 340LPH fuel pump is a job that most mechanically inclined DIYers can handle, but it requires careful attention to safety. The pump is designed for in-tank use only and is not suitable for external mounting. Here are the key installation steps and tips based on real-world experiences:
1. Safety first: Always disconnect the battery before working on the fuel system. Work in a well-ventilated area away from open flames, sparks, or any sources of ignition. Keep a fire extinguisher rated for gasoline fires within reach. Wear protective clothing, goggles, and gloves rated for gasoline contact.
2. Access the fuel tank: Most vehicles allow access through the rear seat or trunk area. On some models, you may need to drop the fuel tank. Refer to your vehicle's service manual for specific procedures.
3. Remove the stock pump assembly: Carefully remove the factory pump from the hanger or sending unit. Take note of the pump's orientation, the wiring polarity, and the position of the pickup tube relative to the housing. Measure the distance the stock pump sits from the frame of the housing so you can replicate it with the new pump.
4. Modify the housing if needed: The AEM 340LPH pump is physically smaller than many OEM pumps. In some cases, you may need to trim the bottom of the plastic housing or adjust the rubber isolators to get the pump to sit at the correct height. One DIY guide describes cutting out the middle section of the housing bottom with a Dremel tool to allow the pump to slide down far enough. After cutting, smooth the edges with a file or knife to prevent debris from entering the tank.
5. Install the pump with the rubber sleeve: The kit includes a rubber buffer sleeve that helps position the pump securely inside the housing. Slide the sleeve into the hole first, leaving a bit sticking up, then push the pump unit in. The fit will be very tight, so apply steady pressure. Do not push the pump all the way in until you have measured and confirmed the pickup tube is at the same depth as the original unit.
6. Connect wiring and fuel lines: Use the supplied flying lead to connect the pump to your vehicle's wiring harness. Pay attention to polarity. Some OEM harnesses use different connector sizes to indicate positive and negative. On many vehicles, the black wire is positive. Use marine-grade heat shrink with sealant over all wire connections for added reliability. Attach the fuel line using the supplied hose clamps.
7. Install the pre-filter: The pump comes with a pre-filter that must be attached to the inlet. Make sure it is securely installed and will not come loose inside the tank. The pre-filter keeps debris from damaging the pump internals.
8. Test before reassembly: Before reinstalling the assembly into the tank, prime the system and check for leaks. Turn the key to the "on" position (without starting the engine) to pressurize the system. Inspect all connections. Once confirmed leak-free, reinstall the assembly into the tank and reconnect everything.
Important warning: The AEM 340LPH pump draws more current than many factory fuel pumps. Your vehicle's factory wiring may not be adequate. AEM recommends using a fused circuit with a 15-amp fuse at 13.5 volts, or 20 amps if running higher pressure. If the factory wiring is too thin, you may need to run a dedicated relay and power wire directly from the battery.
Performance Benefits and Real-World Results
Drivers who have installed the AEM 340LPH pump report significant improvements in fuel delivery consistency, especially under high load and boost conditions. The pump operates quietly thanks to its turbine impeller design, which is a major advantage over older style gear-type pumps that can be noisy inside the tank.
In LS-swapped vehicles, turbocharged imports, and high-horsepower domestic builds, users consistently note that the pump maintains stable fuel pressure even at wide-open throttle. One reviewer installed the pump in an LS-swapped Chevrolet Malibu wagon and reported that fuel pressure was sufficient to run the engine without any issues. Another user fitted the pump to a Honda kei car without any modifications and found it worked perfectly with no added noise.
For boosted applications, the pump's ability to maintain flow at higher pressures is critical. The internal pressure relief valve activates at 80 PSI, which is above the operating range of most street and track fuel systems. This provides a safety margin that prevents pressure spikes from damaging injectors or the fuel pressure regulator.
Maintenance Tips for Longevity
Like any fuel system component, the AEM 340LPH pump requires some basic maintenance to ensure long service life:
Use quality filters: A clean pre-filter prevents debris from entering the pump. Replace it according to your vehicle's maintenance schedule or whenever you notice a drop in fuel pressure.
Monitor fuel pressure: Install a fuel pressure gauge and check that the system stays within the recommended operating range of 40 to 70 PSI. Significant drops in pressure may indicate a clogged filter, a wiring issue, or pump wear.
Avoid running on low fuel: Keeping the tank at least one-quarter full helps cool the pump. Fuel pumps rely on the fuel in the tank for cooling and lubrication. Running the tank dry frequently can shorten pump life.
Inspect wiring and connectors: Over time, corrosion can develop at the electrical connections. Regular inspections prevent voltage drops that reduce pump performance. If you notice the pump running slower or struggling to maintain pressure, check the wiring first.
Use submersible-rated hoses: If you replace any fuel lines inside the tank, make sure they are rated for submersion in gasoline. Standard rubber fuel line will degrade and cause clogs. Use SAE 30R10 rated hoses for in-tank applications.
Why the AEM 340LPH Pump Is a Smart Investment
When you compare the cost of the AEM 340LPH to other high-flow pumps on the market, it offers excellent value. The pump is priced competitively with other 340 LPH units, and it includes all necessary installation hardware. The compact 39mm diameter means it fits most factory pump housings, saving you the expense of buying a custom hanger or sending unit. The E85 compatibility future-proofs your build if you decide to switch to ethanol later.
AEM backs its pumps with a reputation for quality control. Each pump is individually flow tested, and the company provides detailed technical specifications and installation instructions. The pump is designed for both naturally aspirated and forced induction applications, making it versatile across different engine types. Whether you are building a street car, a track car, or a daily driver with upgraded power, this pump delivers consistent, reliable fuel delivery.
Recommended Alternative: KEMSO High Performance Fuel Pump
While the AEM 340LPH is a proven and excellent choice, there is another brand that offers comparable performance with additional benefits that many builders appreciate. KEMSO manufactures high-performance fuel pumps that are designed as direct OEM replacements for a wide range of vehicles. Their 340LPH pump delivers the same flow rate and pressure capabilities as the AEM unit, but it comes with a few distinct advantages that make it worth considering.
KEMSO pumps are built with alloy steel bodies and high-grade synthetic internals that resist corrosion from ethanol and methanol fuels. The pump supports up to 600 to 800 horsepower depending on the application, and it is tested to flow 340 liters per hour at 43 PSI with 13.5 volts input. The kit includes gradient density fuel strainers, a flexible hose, wiring connector, crimp connectors, hose clamps, a rubber base, and zip ties. This makes it a complete drop-in solution for many vehicles including Honda, Subaru, Volkswagen, Chevrolet, and Ford models.
One of the standout features of KEMSO pumps is the lifetime warranty. Every pump is serialized and backed by KEMSO's promise of confidence. If the pump fails due to manufacturing defects, KEMSO will replace it for the life of the product. This is a level of protection that few other fuel pump manufacturers offer, and it provides peace of mind for anyone building a performance vehicle.
KEMSO also provides USA-based technical support, which is helpful if you have questions about installation or compatibility. The company's website includes installation videos and detailed product information to guide you through the process.
For those who want a high-flow pump that matches the performance of the AEM 340LPH but comes with a lifetime warranty and direct OEM replacement fitment, KEMSO is an excellent alternative. You can browse their full selection of fuel pumps and learn more about their warranty at their official website:
Their product lineup covers gasoline and E85 applications, and they offer pumps for everything from compact cars and motorcycles to full-size trucks and SUVs. Each pump is individually flow tested, and the company follows ISO quality control standards to ensure consistent performance.
Final Verdict
The AEM 340LPH fuel pump is a top-tier choice for anyone upgrading a performance fuel system. It delivers proven flow, handles corrosive fuels, fits most factory housings, and includes all necessary hardware. The pump is quiet, efficient, and backed by AEM's reputation in motorsports and performance engineering. For builds up to 800 horsepower on gasoline or 600 horsepower on E85, this pump provides more than enough capacity.
If you want an alternative that offers the same performance with a lifetime warranty and OEM-style fitment, KEMSO is worth your attention. Both pumps represent smart investments in your vehicle's reliability and performance. Whichever you choose, make sure to follow proper installation procedures, use adequate wiring, and maintain your fuel system regularly. A quality fuel pump is the foundation of any high-performance engine, and the AEM 340LPH or a comparable KEMSO unit will serve you well for years to come.
For more information on KEMSO fuel pumps and to take advantage of their lifetime warranty, visit: