300LPH Maximum Flow with High-Pressure Capability
CarBole advertises this pump as a 300LPH high-flow fuel pump, but its supplied specifications provide more useful information at different operating pressures.
Listed flow specifications include:
Maximum Advertised Flow: Up to 300LPH @ 43 PSI / 13.5V
Test Flow: 255LPH @ 43 PSI
High-Pressure Test Flow: 200LPH @ 75 PSI
These specifications demonstrate an important characteristic of electric fuel pumps:
Flow decreases as pressure increases.
That’s particularly important when choosing a pump for a turbocharged engine.
A pump advertised at 300LPH doesn’t necessarily provide 300LPH when the fuel system is operating at elevated rail pressure.
Built for Turbocharged EFI Applications
A turbocharged engine requires progressively more fuel as airflow and boost increase.
If the vehicle uses a boost-referenced fuel-pressure regulator, fuel pressure also rises with boost.
For example, a system with approximately 43 PSI base pressure running 25 PSI of boost could require the pump to deliver fuel against roughly 68 PSI of rail pressure.
At that point, the pump’s high-pressure flow capability becomes far more important than its maximum advertised rating.
The CarBole’s specified 200LPH flow at 75 PSI provides a useful reference when evaluating the pump for higher-pressure applications.
Always calculate required flow at the maximum expected operating pressure before using the pump in a high-horsepower build.
10AN Inlet and 6AN Outlet
The CarBole external fuel pump features performance-oriented AN connections that simplify integration into custom fuel systems.
Inlet: 10AN
Outlet: 6AN
The large inlet helps provide an unrestricted fuel supply to the pump, while the 6AN outlet allows integration with common performance EFI plumbing.
When designing the system, consider the complete fuel path:
Tank/Fuel Cell → Pre-Filter → 10AN Feed → Pump → 6AN Outlet → Post-Filter → Fuel Rail → Regulator
Avoid unnecessarily restrictive fittings or hoses upstream of the pump.
A 300LPH pump can only work with the fuel you actually allow it to receive.
Mount the Pump Below the Fuel Tank
CarBole recommends installing the pump below the fuel tank so fuel can gravity-feed the inlet.
That’s important because high-pressure external EFI pumps are generally better at pushing fuel than pulling it over long distances.
A good installation should provide the pump with a reliable, unrestricted fuel supply.
Avoid mounting the pump:
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Excessively high above the tank
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Far away from the fuel source
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Near excessive exhaust heat
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Where road debris can easily damage it
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Where fuel lines can kink
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Where electrical terminals remain exposed
The supplied mounting bracket helps secure the pump to the vehicle.
Professional installation is recommended when designing a custom external fuel system.
Use a Pre-Filter
CarBole recommends using a pre-filter with this pump.
A properly selected pre-filter helps protect the pump from contamination originating inside the tank or fuel cell.
Filtration is especially important with external performance pumps because contamination can damage internal pump components and reduce service life.
Make sure the pre-filter is suitable for use on the inlet side of an EFI fuel pump and provides sufficient flow without creating excessive restriction.
A post-pump EFI filter may also be appropriate depending on the fuel-system design.
Gasoline and Diesel Compatible
The CarBole 300LPH pump is specified for use with:
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Gasoline
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Diesel fuel
This gives it flexibility for custom EFI applications using conventional petroleum-based fuels.
Fuel-system components upstream and downstream should still be compatible with the fuel being used.
Not Recommended for E85
This distinction is important:
CarBole does not recommend this pump for E85 or alcohol-based fuels.
According to the supplied product specifications, using alcohol/E85 fuel can reduce the working life of the pump.
If you’re building an ethanol-fueled vehicle, choose a pump specifically engineered and rated for E85 instead.
Our How to Convert to E85 guide explains why pump materials, seals, hoses, injectors and other fuel-system components all need to be considered during an ethanol conversion.
Don’t assume that because an electric pump physically moves E85, it’s actually designed to live in an ethanol fuel system.
Those are two very different achievements.
Planning an E85 Build Instead?
If your current gasoline project may eventually move to E85, consider that future requirement before building the entire fuel system.
Replacing the pump later can mean changing filters, hoses, seals and other components at the same time.
Our guide to upgrading fuel lines for E85 covers the plumbing considerations involved with ethanol conversions.
For a dedicated E85 build, an explicitly ethanol-compatible pump is the better choice.
Match the Pump With Your Fuel Injectors
Pump capacity is only one side of fuel-system sizing.
The injectors still need sufficient capacity to supply the engine at the intended horsepower level.
Our guide covering fuel injector upgrade benefits explains how injector flow and duty cycle relate to modified engines.
For turbocharged and high-output applications, size the pump and injectors around the same horsepower goal.
A massive pump feeding undersized injectors is still an undersized fuel system.
Return-Style Fuel System Applications
An external pump like the CarBole 300LPH is particularly well suited to custom return-style EFI fuel systems.
A typical configuration can use:
Fuel Tank → Pre-Filter → Pump → EFI Filter → Fuel Rail → Adjustable Regulator → Return Line → Tank
The regulator maintains the desired rail pressure while excess fuel returns to the tank.
If you’re deciding how to configure your system, read our guide comparing returnless versus return fuel systems.
Make sure the regulator and return line can handle the pump’s available flow without creating pressure-control problems.
12V EFI Systems Only
The CarBole pump is designed specifically for 12V EFI fuel systems.
Electrical supply directly affects fuel-pump performance.
For a custom installation, use appropriately sized:
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Power wiring
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Ground wiring
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Relay
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Fuse protection
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Electrical terminals
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Weather protection
Follow the polarity markings at the pump’s electrical terminals.
The positive and negative connections are positioned near the fuel outlet and should be connected according to the pump markings.
Never guess the polarity.
Apparently electricity remains stubbornly unwilling to recognize “close enough” as a wiring standard.
Installation Hardware Included
The CarBole 300LPH fuel-pump package includes:
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1 × External Electric Fuel Pump
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1 × Mounting Bracket
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1 × Inlet Adapter
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1 × Outlet Adapter
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1 × One-Way Check Valve
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2 × Gaskets
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2 × Nuts
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2 × Electrical Terminals
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2 × Terminal Covers
Additional fuel hose, filters, AN fittings, wiring, relay and vehicle-specific hardware may be required.
Ideal Applications
The CarBole 300LPH external inline fuel pump is a potential choice for:
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Gasoline performance builds
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Diesel applications
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Turbocharged EFI engines
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Engine swaps
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Custom EFI conversions
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Fuel-cell installations
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Street/strip vehicles
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Track cars
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Modified street vehicles
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Custom return-style fuel systems
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Projects requiring an external high-pressure pump
It is not recommended for E85 or alcohol-fuel applications.
Why Choose the CarBole 300LPH External Fuel Pump?
The CarBole external pump combines high-flow EFI capability, external mounting and performance-oriented 10AN/6AN connections in an affordable universal package.
Its specified flow at both 43 PSI and 75 PSI also gives builders more useful information than a single maximum-flow number.
For custom gasoline or diesel EFI applications, it provides a straightforward route to increased fuel capacity without modifying an in-tank pump assembly.
Mount it properly, supply it with adequate fuel through a pre-filter, provide a strong electrical circuit and size the rest of the system around the engine’s actual requirements.
And if you’re running E85? Pick an E85 pump. Saving a few dollars on the one component responsible for keeping a boosted engine from going lean is a particularly creative form of financial planning.
Product Specifications
Brand: CarBole
Product Type: High-Flow External Inline Electric Fuel Pump
Maximum Advertised Flow: Up to 300LPH @ 43 PSI / 13.5V
Test Flow: 255LPH @ 43 PSI
High-Pressure Flow: 200LPH @ 75 PSI
Voltage: 12V DC
Fuel System: EFI only
Fuel Compatibility: Gasoline and diesel
E85 Compatibility: Not recommended
Alcohol Fuel Compatibility: Not recommended
Inlet: 10AN
Outlet: 6AN
Installation: External / Inline
Recommended Mounting: Below fuel tank / gravity-fed
Pre-Filter: Recommended
Mounting Bracket: Included
Check Valve: Included
Fitment: Universal / custom installation
Fitment Note: This is a universal external performance fuel pump requiring custom installation. Verify required fuel flow, pressure, fuel compatibility, AN plumbing, electrical requirements and mounting position before ordering.
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