Electric Fuel Pumps: Your UK Guide to Buying & Installation

When it comes to enhancing your vehicle's performance or transitioning to a modern fuel injection system, the humble fuel pump often becomes a central point of discussion. It's the unsung hero that ensures your engine receives a consistent, high-pressure supply of fuel, directly impacting reliability and power output. Whether you're upgrading a classic Mustang for EFI or simply replacing a worn-out component, understanding your options and making the right choice is paramount. This guide will navigate the complexities of acquiring and installing fuel pumps, especially for those considering the leap to electronic fuel injection (EFI).

Where Can I Buy a Fuel Pump?

Finding a reliable source for a quality fuel pump is the first step in any upgrade or replacement project. The market offers a vast array of options, from general automotive parts suppliers to specialist performance retailers. For those in the UK, particularly when dealing with performance or motorsport-grade components, specific suppliers stand out.

One highly reputable source, as highlighted by expert opinion, is Demon Tweeks. They are renowned as the UK’s leading Motorsport and Performance retailer, boasting over 50 years of experience in the field. Their extensive range of fuel pumps, available both online and in-store, caters to a wide spectrum of needs, from standard replacements to high-performance units for demanding applications. Shopping with specialists like Demon Tweeks ensures you're accessing products designed for longevity and maximum benefit, backed by expert advice.

Beyond specialist retailers, you can also find fuel pumps at:

• Main Dealerships: For genuine OEM parts, ensuring perfect fit and function, albeit often at a premium.
• Independent Automotive Parts Stores: These can offer a good balance of price and accessibility for standard replacement pumps.
• Online Automotive Marketplaces: Websites like eBay or Amazon can provide a wide selection, but diligence is required to verify seller reputation and product authenticity.
• Performance Tuning Shops: Many local tuning shops not only sell but also install performance fuel systems, offering valuable hands-on advice.

Regardless of where you purchase, always prioritise suppliers known for quality components and excellent customer service. The fuel pump is a critical component; cutting corners here can lead to significant issues down the line.

Will a Small Electric Fuel Pump Work for My EFI Conversion?

This is a common question, especially for owners of classic cars like a '69 Mustang with a small block and carburettor, looking to transition to a self-learning EFI system. The allure of a seemingly simpler, externally mounted electric fuel pump is strong, avoiding the perceived hassle of dropping the fuel tank. However, as automotive expert Jeff Smith points out, while technically it 'will work', there are significant caveats.

The Challenges of an External, Inline Pump

Installing a small, inline electric fuel pump, such as a Bosch unit, outside the tank might seem straightforward. You can plumb a large delivery fuel line, install the proper fuel pressure regulator, and even create a return system using the original fuel line by adding a return bung to the stock sending unit. All of this can be relatively easy to accomplish.

The core problem arises when the fuel level in the tank drops. Under acceleration, especially with a low fuel tank, the fuel can slosh away from the stock pickup. When this happens, the fuel pressure will immediately plummet to near zero, causing the engine to sag badly. This sudden loss of power will then allow the fuel to slosh forward, temporarily restoring pressure, only for the cycle to repeat as you accelerate again. As Jeff Smith succinctly puts it, this scenario is "basically lame." While keeping the fuel tank half-full or more would mitigate this issue, it effectively halves your cruising range, which is hardly a practical solution for a classic car.

The fundamental issue is that external pumps are designed to push fuel, not to pull it efficiently over long distances or from a non-submerged pickup. An in-tank pump, by contrast, is constantly submerged in fuel, ensuring a consistent supply to the pump inlet, even during aggressive driving or when the tank is low.

The Rise of Fuel Sump/Surge Tank Conversion Kits

Fortunately, innovations in the aftermarket have provided more effective solutions that minimise installation headaches while delivering the required high-pressure fuel for EFI. Companies like Edelbrock and FiTech have developed universal fuel sump or surge tank conversion kits. Think of these as a compact fuel reservoir with a high-pressure electric fuel pump housed inside.

How They Work:

These systems typically hold around 2 litres of fuel and are fed by your existing mechanical fuel pump. The surge tank is mounted in the engine compartment, usually between the inner fender well and the firewall, utilising available space. A fuel hose connects the outlet of your mechanical pump to the inlet of the surge tank. Inside the tank, a float system regulates the fuel level, ensuring the internal high-pressure electric fuel pump (e.g., a 340 litres-per-hour (lph) pump capable of feeding 750-800 horsepower in the FiTech system) is always submerged and supplied with fuel.

A filter cleans the fuel before it enters the high-pressure pump, which then feeds the EFI throttle body at the required pressure (e.g., 43 psi or 58 psi). Unlike traditional in-tank EFI systems, the 'return' is built into the surge tank itself. The bypass occurs internally, and because the distance between the surge tank and the EFI throttle body is relatively short, pressure remains constant.

Advantages of Surge Tank Systems:

• Ease of Installation: Significantly simpler than a full in-tank, return-style system, as it avoids dropping the fuel tank and running new return lines.
• Utilises Existing Mechanical Pump: Leverages your current low-pressure mechanical pump to feed the surge tank.
• Consistent Pressure: Provides a steady, high-pressure fuel supply to the EFI system, eliminating the fuel starvation issues of simple external pumps.
• Portability/Reversibility: If you decide to sell the car without the EFI system later, the surge tank can be easily removed, and the carburettor quickly re-installed.
• Compact Design: Units like the FiTech Fuel Command Center are compact enough to fit under most bonnets (approx. 8 5/8-inch tall and 6 ½ inches deep).

Disadvantages and Safety Concerns:

While convenient, surge tanks do introduce some considerations:

• Fuel Under the Bonnet: The most significant concern is placing a small reservoir of fuel in the engine compartment. While designers aim for safe locations, any fuel system component under the bonnet carries an inherent, albeit small, risk in the event of an accident. Careful placement is key.
• NHRA Rules: It's crucial to note that rules from organisations like NHRA (National Hot Rod Association) prohibit mounting fuel lines, regulators, or fuel tanks like this on the firewall of a car. Furthermore, under no circumstances should this tank be mounted inside the passenger compartment.
• Cost: While easier to install, the component cost for a surge tank system (around £400 for the FiTech unit) is comparable to that of a dedicated in-tank pump system.

The Dedicated In-Tank Pump System: The Gold Standard

For many, the ultimate solution for an EFI conversion remains a dedicated in-tank pump system, such as the Aeromotive Phantom system. While it requires more effort and potentially more cost due to the need for a separate high-pressure feed line, AN fittings, filters, and a dedicated return line, it offers unparalleled reliability and safety.

An in-tank pump is constantly submerged in fuel, keeping it cool and ensuring a continuous, cavitation-free supply. This eliminates any risk of fuel starvation due to sloshing, even with a nearly empty tank. For a long-term solution, especially if you plan to keep the car for an extended period or push its performance limits, an in-tank conversion is generally the recommended approach.

Here's a comparison of the systems discussed:

Key Considerations When Choosing a Fuel Pump

Beyond the type of pump, several factors should influence your decision:

• Horsepower Rating: Ensure the pump's flow rate (e.g., lph) is sufficient for your engine's current and future horsepower demands. Always factor in a safety margin.
• Fuel Type Compatibility: If you plan to run E85 or other alternative fuels, ensure the pump and all fuel system components are compatible with their corrosive properties.
• Fuel Pressure Requirements: EFI systems typically require much higher fuel pressure (e.g., 43-58 psi) than carburettors (e.g., 5-7 psi).
• System Integration: Consider the entire fuel system – lines, fittings, and especially the fuel pressure regulator. A high-quality regulator is crucial for stable EFI operation.
• Noise Levels: Some external pumps can be quite noisy. In-tank pumps are generally quieter as the fuel acts as a sound dampener.
• Future-Proofing: If you anticipate further engine modifications that will increase horsepower, choose a pump that can handle future demands to avoid having to upgrade again.

Frequently Asked Questions (FAQs)

Q1: What is the main difference between a mechanical and an electric fuel pump?

Mechanical fuel pumps are typically engine-driven, using a camshaft lobe or eccentric to operate a diaphragm. They produce lower pressure and are common in older carburetted vehicles. Electric fuel pumps use an electric motor to create pressure, can be mounted anywhere in the fuel line (though ideally in-tank), and are capable of much higher pressures required for EFI systems.

Q2: Why do EFI systems need a return line, and do all electric pumps need one?

EFI systems need a return line to circulate excess fuel back to the tank. This helps regulate fuel pressure, cools the fuel, and prevents vapour lock. Most high-pressure electric pumps designed for EFI require a return system to maintain stable pressure, though some newer 'returnless' systems exist, and surge tanks incorporate an internal return.

Q3: Can I use a carburettor fuel pump with an EFI system?

No, generally you cannot. Carburettor fuel pumps operate at much lower pressures (typically 5-7 psi) than what EFI systems require (40-60 psi). Using a carburettor pump with EFI will result in insufficient fuel delivery and poor engine performance.

Q4: How do I know what size (lph) fuel pump I need?

The size of the fuel pump (measured in litres per hour, lph, or gallons per hour, gph) depends on your engine's horsepower output. There are various online calculators and charts available, but as a rough guide, a 200 lph pump is often sufficient for naturally aspirated engines up to 550 hp, while higher horsepower or forced induction setups will require larger pumps (e.g., 340 lph for 750-800 hp).

Q5: What are the main safety concerns with aftermarket fuel pumps?

The primary safety concerns include potential fuel leaks from improper installation or component failure, and the risk of fire, especially if fuel is stored under the bonnet in an accident-prone area. Always use high-quality, fuel-rated lines and fittings, ensure proper electrical wiring with relays and fuses, and adhere to any relevant motorsport or regulatory guidelines regarding fuel system component placement.

Conclusion

Deciding on the right fuel pump for your vehicle, especially when considering an EFI conversion, boils down to balancing ease of installation, cost, and long-term performance and reliability. While a simple external electric pump might seem like an easy fix, its inherent drawbacks make it a less-than-ideal solution for anything beyond basic needs. Surge tank systems offer a compelling compromise, providing the necessary high-pressure fuel for EFI with significantly reduced installation complexity compared to a full in-tank conversion.

However, for the ultimate in reliability, safety, and performance, particularly if you plan to keep your vehicle for the long haul or push its limits, a dedicated in-tank pump system remains the preferred choice. Always procure your components from reputable suppliers like Demon Tweeks and ensure that installation is carried out meticulously, adhering to all safety guidelines. Your engine's performance and longevity depend on it.

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