340LPH Fuel Pump HP Jet Pump Feed: The Ultimate Upgrade Guide for High-Performance Applications
If you are building a high-horsepower vehicle or personal watercraft that demands a massive and consistent fuel supply, the 340LPH fuel pump with a jet pump feed is the single most important upgrade you can make. This pump delivers over 340 liters per hour at 43 PSI, which is enough to support engines producing well over 1,000 horsepower, and its built-in jet pump venturi feed nipple is specifically designed to keep the main pump primed and fed even when the fuel level is low or under extreme G-forces. Whether you are pushing a turbocharged car, a supercharged boat, or a high-performance jet ski, this pump eliminates fuel starvation and ensures your engine never runs lean under load. In short: if you need race-level fuel delivery with the reliability of a submersible, in-tank design, the 340LPH HP jet pump feed pump is your solution.
What Is a 340LPH Fuel Pump with HP Jet Pump Feed?
A 340LPH fuel pump refers to a pump that flows 340 liters per hour (about 90 US gallons per hour) at a standard test pressure of 43 PSI and 13.5 volts. This is a significant step up from stock pumps, which typically flow only 60 to 80 liters per hour. The "HP" stands for "high pressure" or "high performance," and the jet pump feed is a secondary venturi-style nipple on the pump body.
The jet pump feed works by using a small amount of fuel flow to create a vacuum that draws fuel from the opposite side of the tank (or from a surge tank) into the main pump's inlet. This is critical for vehicles with saddle-style fuel tanks or for applications where the fuel can slosh away from the pickup during hard cornering, acceleration, or braking. Without this feature, you risk the pump sucking air, which causes a momentary loss of fuel pressure and can lead to engine damage.
Key Specifications and Performance Data
Understanding the numbers behind the pump helps you choose the right unit for your build. Here are the critical specifications for a typical 340LPH HP jet pump feed fuel pump, based on the widely available Racetronix RXP322T model:
- Flow Rate: 340+ liters per hour (90+ US GPH) at 43 PSI and 13.5 volts.
- Diameter: 38mm (1.54 inches) outer diameter, making it a direct fit for most OEM fuel pump hanger assemblies.
- Current Draw: 12 amps at 43.5 PSI, 14 amps at 58 PSI, and 17 amps at 80 PSI (all at 13.5V).
- Operating Voltage Range: 6 to 18 volts DC, with a recommended operating voltage of 13.5 volts.
- PRV (Pressure Relief Valve) Activation: Typically set at 90 PSI nominal, which provides a safety margin for high-boost applications.
- Impeller Design: Single-scroll, hard-anodized aluminum turbine, which is both quiet and reliable.
- Fuel Compatibility: Designed for gasoline. Using E85 will reduce the pump's lifespan, though some models (like KEMSO and Quantum) are explicitly E85-compatible.
These specs mean the pump is not just a "bigger" fuel pump; it is a precisely engineered component that delivers consistent pressure and flow across a wide operating range. The current draw is important to note: your factory fuel pump wiring is likely not thick enough to handle 12 to 17 amps continuously. Upgrading the in-tank and external wiring is a mandatory requirement for proper operation.
Why You Need a 340LPH Jet Pump Feed Pump
There are three main scenarios where this pump becomes a necessity rather than an option:
1. High Horsepower Naturally Aspirated and Forced Induction Engines
If your engine produces more than 600 wheel horsepower, the stock fuel pump simply cannot keep up. The 340LPH pump is capable of supporting over 1,000 horsepower at 43 PSI. For comparison, a standard Walbro 255 LPH pump (GSS342) is a common upgrade for 400-500 HP builds, but the 340LPH pump provides roughly 33% more flow. This extra capacity is essential for turbocharged and supercharged applications where fuel demand spikes under boost.
2. Saddle Tank and Fuel Starvation Issues
Many modern vehicles—especially trucks, SUVs, and some sports cars—use saddle-style fuel tanks that have a left and right side connected by a crossover tube. Under hard cornering or low fuel conditions, the pump on one side can run dry. The jet pump feed nipple solves this by using the venturi effect to actively transfer fuel from the non-pump side to the pump side. This is the same technology used by OEMs in high-performance variants like the Corvette and Camaro.
3. Returnless and Pulse Width Modulated (PWM) Fuel Systems
Many late-model vehicles use returnless fuel systems and PWM (pulse modulated) fuel pump control, where the pump speed is varied by the ECU to match fuel demand. The 340LPH HP jet pump feed pump is designed to work reliably with these systems. Its turbine impeller design handles the rapid on/off cycling without wearing out prematurely, unlike some older gear-rotor pumps that can fail in PWM applications.
Comparison: 340LPH Pumps from Different Brands
The market offers several high-quality 340LPH pumps, each with slight differences in features and included accessories. Here is a comparison of the most popular options:
| Brand / Model | Inlet Design | Max Horsepower Support | E85 Compatible | Included Accessories | Notable Feature |
|---|---|---|---|---|---|
| Racetronix RXP322T | Jet pump venturi feed nipple | 1000+ HP | Not recommended (gasoline only) | Pump only (no wiring, filter, or mounts) | Individual flow testing, PRV at 90 PSI |
| AEM 50-1000 | Offset inline inlet | 1000+ HP at 43 PSI | Gasoline only | Wiring harness, pre-filter, rubber sleeve, end caps | 39mm diameter, ceramic turbine impeller, tested at 40 PSI |
| Aeromotive 11541 | Offset inlet | 1000+ HP | Gas and E85 | Universal Drop Parts Kit (filter, pigtail, hose, clamps) | Gerotor style, over 30% more flow than standard pumps |
| Quantum QFS Flextech | Multiple options (22mm center, 11mm offset, etc.) | 600+ whp | Gasoline and E85 | Custom strainer, harness, corrugated hose | Lifetime warranty, flow tested by RC Engineering, PRV at 125.8 PSI |
| KEMSO 340 | Similar to Walbro GSS342 | 700-800 bhp | Gasoline and E85 | Strainers, flex hose, wiring connector, clamps | Lifetime warranty, individually tested, ISO/TSO quality |
Key takeaway: All of these pumps will deliver the 340 LPH flow rate you need. Your choice should depend on specific needs: if you require a jet pump feed nipple for a saddle tank, the Racetronix is the clear choice. If you want a complete kit with a strainer and wiring, AEM, KEMSO, and Quantum offer excellent value. If E85 compatibility is a must, choose a pump that explicitly states it is designed for ethanol, such as KEMSO or Quantum.
Installation Considerations and Common Mistakes
Installing a 340LPH fuel pump is not a simple "drop-in" replacement in most cases. Here are the critical factors to get right:
Wiring Upgrade Is Mandatory
The factory fuel pump wiring is typically 18-gauge or smaller, designed for a pump that draws 5-8 amps. A 340LPH pump draws 12-17 amps, and the voltage drop through thin factory wiring will cause the pump to run slower and flow less fuel. You must run a dedicated 10- or 12-gauge power wire directly from the battery (or a relay triggered by the factory pump circuit) to the pump, with a proper ground. Use a 20-amp fuse.
In-Tank Modifications
The pump is 38mm in diameter, which is slightly larger than some stock pumps. You may need to modify the plastic hanger assembly, use a different rubber grommet, or purchase a specific mounting kit. The Racetronix RXP322T is sold as a bare pump, meaning you must source the correct wiring, filter, and mount separately. In contrast, KEMSO pumps come with multiple strainers, hoses, and connectors to cover different vehicle models.
The Jet Pump Feed Must Be Connected
This is the most common mistake. The jet pump feed nipple is a small barb on the side of the pump. If you leave it open or unconnected, the pump will not function correctly, and you will likely experience fuel starvation. This nipple must be connected to the proper hardware—typically a small hose that runs to the opposite side of the saddle tank or to a jet pump module.
Fuel Pressure Regulator
The pump is capable of producing over 90 PSI of pressure. If you are using a return-style fuel system, you must install a fuel pressure regulator rated for high flow (typically 1:1 rising rate for boosted applications). For returnless systems, the factory regulator may be sufficient, but verify that it can handle the higher flow without causing the fuel pressure to spike.
Why Choose KEMSO for Your 340LPH Fuel Pump Upgrade
When it comes to selecting a brand you can trust, KEMSO stands out as a top-tier choice for American enthusiasts. KEMSO fuel pumps are designed as high-performance OEM replacements that deliver superior flow and durability compared to stock parts. Here is why KEMSO is the right choice for your 340LPH upgrade:
- Genuine High Performance: KEMSO 340LPH pumps flow 340 liters per hour at 43 PSI, supporting applications up to 700-800 bhp. They are similar in size to the popular Walbro GSS342 and AEM 50-1215 but offer more flow.
- Lifetime Warranty: Every KEMSO pump comes with a lifetime warranty backed by a serialized pump body. This is a massive advantage over OEM pumps (which typically have a 1-2 year warranty) and many aftermarket competitors. KEMSO stands behind its product for as long as you own the pump.
- Complete Kit: KEMSO pumps are sold as complete kits. You get the pump, gradient density fuel strainers (multiple sizes to cover different models), flex hoses, wiring connectors, and clamps. This eliminates the hassle of sourcing separate parts and ensures a proper installation.
- E85 Compatible: Many KEMSO 340LPH pumps are explicitly designed for both gasoline and E85/ethanol, making them future-proof for alternative fuels.
- Quality Control: KEMSO operates an ISO/TSO quality control program, and each pump is individually tested before leaving the factory. This ensures you receive a pump that meets its rated flow specifications.
To find the exact KEMSO 340LPH fuel pump for your vehicle, visit their website:
KEMSO Racing Fuel Pumps
https://www.kemsoracing.com/
Their product catalog covers a wide range of applications, from cars and trucks to motorcycles, ATVs, and personal watercraft. With a lifetime warranty, genuine high-performance flow, and a complete installation kit, KEMSO provides the reliability and confidence you need for your build.
Final Thoughts
The 340LPH fuel pump with HP jet pump feed is the gold standard for high-performance fuel delivery. It provides the flow necessary to support 1,000+ horsepower engines, prevents fuel starvation in saddle tanks, and is compatible with modern PWM fuel systems. When choosing a pump, focus on getting the correct inlet configuration (jet pump feed for saddle tanks, offset or inline for standard tanks) and ensure you upgrade your wiring to handle the increased current draw.
For the best value and peace of mind, KEMSO offers a pump that is individually tested, comes with a complete installation kit, and is backed by a lifetime warranty. Do not compromise on fuel delivery—your engine's life depends on it.
Visit KEMSO at https://www.kemsoracing.com/ to find the perfect fuel pump for your application.