Understanding Facet Fuel Pumps for Carburettors

For enthusiasts and mechanics alike, understanding the intricate workings of a vehicle's fuel system is paramount. When it comes to carburettor-fed engines, particularly in classic cars, rally machines, or custom builds, the fuel pump plays a critical role in ensuring a consistent and reliable fuel supply. Facet electric fuel pumps have long been the go-to choice for many, renowned for their dependability and performance in a wide array of road and light competition applications. Unlike mechanical pumps, electric pumps offer a steady fuel flow independent of engine RPM, a significant advantage for maintaining consistent pressure and preventing fuel starvation under demanding conditions. This article delves into the distinct ranges of Facet fuel pumps available, helping you navigate their features, benefits, and ideal applications.

The Core Ranges of Facet Fuel Pumps

Facet has established itself as a leading name in electric fuel pumps for carburettor systems. Over the years, two primary ranges – the Solid State (often referred to as 'cube' pumps) and the Cylindrical pumps – have become industry standards, trusted by countless vehicle owners and motorsport teams. More recently, Facet introduced the Posi-Flow range, an advanced development building upon the Solid State design, bringing enhanced features and performance to the market. Understanding the nuances of each type is crucial for selecting the correct pump for your specific vehicle and its intended use.

Solid State (Cube) Pump: The Reliable Workhorse

The Solid State, often affectionately known as the 'cube' pump due to its distinctive shape, has been a staple in the automotive world for many years. Its compact design and robust construction have made it a popular choice for a variety of carburettor vehicles. This range is characterised by its consistent operation and straightforward design. There are four primary versions within the Solid State series, each tailored to different performance requirements, offering a clear progression in fuel delivery capabilities:

A key characteristic of the Solid State pumps is the absence of a check valve. This means that when the pump is not actively running, fuel can potentially flow back through the system. While this might sound concerning, it rarely poses a significant issue in motorsport or daily road applications where the pump is typically running whenever the ignition is on. Furthermore, these pumps are designed to run constantly, producing a distinctive clicking sound even when the fuel system has reached its maximum pressure and no fuel is actively flowing to the carburettors. This continuous operation ensures that there is always fuel readily available for immediate delivery, providing peace of mind for drivers.

Due to their design, Solid State pumps have a maximum lift capability of approximately 30 centimetres. This crucial specification dictates their optimal installation location: they must be fitted relatively close to the fuel tank, ideally near or below the tank's level, to ensure efficient priming and consistent fuel draw. Ignoring this can lead to fuel starvation or inconsistent performance. The pumps are equipped with 1/8 NPT (National Pipe Taper) ports, a standard fitting in many automotive applications. It is imperative that the inlet port is fitted with an appropriate filter union to protect the pump from contaminants. Facet offers specific filter unions, such as the FPA906, a smaller option, and the FPA930, a larger one featuring a non-replaceable paper filter. Both types screw directly into the inlet and accommodate 8mm push-on unions, simplifying installation. It's also vital to remember that these pumps are designed for negative earth systems only, a common configuration in modern and classic vehicles alike.

Cylindrical Pump: The Competition Favourite

Stepping up in performance and often seen in more demanding competition environments, the Cylindrical pump, easily identifiable by its tubular shape, is another long-standing workhorse in the Facet lineup. These pumps are widely employed in high-performance carburetted competition cars where a robust and consistent fuel supply is non-negotiable. Two prominent versions are the Silver Top (STC505) and the Red Top (RTW506), with the latter being particularly favoured for serious racing applications due to its higher flow rate and pressure capabilities:

Similar to the Solid State range, Cylindrical pumps are generally not fitted with an internal check valve, meaning they also run constantly. This continuous operation ensures a ready supply of fuel, which is crucial in high-performance scenarios where instantaneous fuel delivery can be the difference between winning and losing. A notable feature of the Cylindrical pumps is the availability of alternative pressure springs. For applications requiring a very specific or lower pressure supply without the need for an external pressure regulator, springs offering 2-3 Psi, 4-5 Psi, or 6-7 Psi are available. This customisation allows for fine-tuning the fuel system to match the precise requirements of a particular engine setup, providing flexibility for tuners. These springs can often be fitted by your supplier prior to dispatch, simplifying the installation process.

Maintenance is also a consideration with these pumps; they feature a replaceable internal filter located within the base of the pump. This design facilitates easy cleaning or replacement, ensuring the longevity and efficient operation of the unit. A clever addition is the magnet fitted into the bayonet base cap, designed to attract any magnetic particles that might be drawn into the fuel system, offering an additional layer of protection against debris.

One of the significant advantages of the Cylindrical pumps, especially for installation flexibility, is their impressive maximum dry lift of 60 centimetres. This doubled lift capacity compared to the Solid State pumps means they can be mounted further away from the fuel tank, even at the front of the vehicle, without compromising performance. This increased versatility is particularly beneficial in competition cars where space constraints and weight distribution are critical factors. Union compatibility varies slightly between the models: the Red Top pump typically utilises 1/4 NPT female unions, while the Silver Top models feature 1/8 NPT unions. A wide range of brass push-on unions are available, including straight or 90-degree options, to suit 6mm, 8mm, and 10mm hoses. For those seeking premium connections, Goodridge unions are also compatible. As with the Solid State pumps, Cylindrical pumps are designed exclusively for negative earth electrical systems.

Posi-Flow Fuel Pump: The Modern Evolution

Representing the latest evolution in Facet's fuel pump technology, the Posi-Flow range is a modern development building upon the proven Solid State design. This series aims to combine the reliability of its predecessor with enhanced features, making it an attractive option for contemporary applications. The Posi-Flow pumps offer a refined performance profile, often at a slightly more competitive price point than their Solid State counterparts, making them an excellent value proposition:

The initial Posi-Flow model, the 60106, provides performance equivalent to the well-regarded SS502 Solid State pump, demonstrating its capability for fast road applications. However, where the Posi-Flow truly distinguishes itself is in its versions fitted with internal check valves. Models such as the 60301 and 60302 incorporate this crucial feature, which significantly enhances their functionality.

The primary advantage of the integrated check valve is a dramatic increase in the pump's maximum lift capability, reaching an impressive 127 centimetres. This substantial lift allows for much greater flexibility in mounting location, enabling the pump to be positioned far from the fuel tank without issue. For instance, it could be mounted higher up in the engine bay or at the front of the vehicle, offering solutions for challenging installations. Beyond installation flexibility, the check valve provides a vital benefit, particularly in diesel applications. It effectively prevents the fuel system from draining back when the engine is switched off. This ensures that the fuel lines remain primed, facilitating quicker and more reliable starts, especially beneficial in cold weather or after periods of inactivity. This feature also reduces wear on the pump by preventing it from having to re-prime the entire system each time it starts.

Like the Solid State pumps, Posi-Flow models typically feature 1/8 NPT unions, ensuring compatibility with a wide range of existing fuel lines and fittings. And, consistent with the entire Facet electric fuel pump line-up, they are exclusively designed for negative earth electrical systems, simplifying integration into most vehicle setups.

Choosing the Right Facet Fuel Pump: A Comparative Look

To provide a clearer overview of the differences and help you make an informed decision, here's a comparative summary of the three Facet fuel pump ranges:

From this comparison, it becomes evident that each Facet pump range caters to specific needs. The Solid State pumps are robust and straightforward, ideal for standard road use or light competition where installation near the tank is feasible. Their constant clicking is a familiar sound to many classic car owners, signifying their continuous operation.

The Cylindrical pumps, particularly the Red Top, are designed for the rigours of competition. Their higher flow rates, impressive dry lift, and the option for fine-tuning pressure with interchangeable springs make them a favourite among racers. The internal, replaceable filter also adds a practical element for maintenance in demanding environments.

The Posi-Flow pumps represent the modern evolution, offering the reliability of the Solid State but with the significant enhancement of an integrated check valve. This feature not only boosts their lift capability but also makes them highly suitable for diesel applications by preventing fuel drain-back. For those seeking contemporary performance with improved installation flexibility, the Posi-Flow is an excellent choice. Your selection should ultimately be guided by your vehicle's specific requirements, including engine type, desired fuel flow, and installation constraints.

Frequently Asked Questions About Facet Fuel Pumps

Navigating the world of fuel pumps can bring up several questions. Here are some of the most common queries regarding Facet electric fuel pumps:

Why do Facet electric fuel pumps click constantly?

Facet Solid State and Cylindrical pumps are designed to run constantly when the ignition is on, regardless of whether fuel is flowing to the carburettors or not. The clicking sound is a normal operational characteristic, indicating that the pump is priming the system and maintaining pressure. This continuous operation ensures that fuel is always immediately available, preventing delays or starvation, particularly important in performance applications. The Posi-Flow pumps with a check valve might click less frequently once pressure is built, but will still operate continuously.

Can I use a Facet fuel pump with a fuel-injected engine?

No, Facet electric fuel pumps, as discussed in this article, are specifically designed for vehicles running carburettors. Fuel injection systems require significantly higher fuel pressures (typically 30-60+ PSI) than what these pumps can deliver. Using a Facet carburettor pump with a fuel-injected engine would result in insufficient fuel pressure and poor engine performance. Always ensure your fuel pump matches your engine's fuel delivery system.

What is 'lift' and why is it important for a fuel pump?

'Lift' refers to the maximum vertical distance a fuel pump can draw fuel from the tank to its inlet port. This is a critical specification for installation. If a pump's lift capacity is exceeded by its mounting position relative to the fuel tank, it may struggle to draw fuel effectively, leading to fuel starvation, inconsistent supply, or premature pump failure. Pumps with higher lift capabilities offer greater flexibility in mounting location, allowing them to be placed further from the tank or higher up in the vehicle chassis.

Do I need a pressure regulator with my Facet fuel pump?

In many carburettor applications, especially with higher-pressure Facet pumps like the SS503 or Red Top, a fuel pressure regulator might be beneficial or even necessary. Carburettors typically operate optimally within a narrow pressure range (often 2-5 PSI). While some Facet pumps deliver pressures within this range, others, particularly the competition-spec models, can exceed it. An external pressure regulator ensures that the carburettor receives fuel at the precise pressure it requires, preventing issues like fuel flooding or needle valve bounce, which can lead to poor running or engine damage. Some Cylindrical pumps offer alternative pressure springs to adjust pressure internally, potentially negating the need for an external regulator in specific setups.

Which Facet pump is right for my classic car or competition vehicle?

The ideal Facet pump depends entirely on your vehicle's specific needs. For a standard classic car with a factory carburettor, a lower-pressure Solid State (e.g., SS500 or SS501) or a Posi-Flow 60106 might be sufficient. For fast road or light competition use, the SS502, Posi-Flow 60301, or Silver Top Cylindrical pump could be more appropriate. Serious competition vehicles often benefit from the higher flow and pressure of the SS503, Red Top Cylindrical, or Posi-Flow 60302. Consider your engine's fuel consumption, existing carburettor pressure requirements, and available mounting space when making your choice. Always consult your vehicle's specifications or a reputable mechanic if unsure.

What does 'negative earth only' mean for these pumps?

'Negative earth only' indicates that the pump is designed to be used in vehicles where the negative terminal of the battery is connected to the vehicle's chassis (earth). This is the most common electrical system configuration in modern and many classic vehicles. If your vehicle has a positive earth system (less common, typically found in very old British cars), you would need to either convert your vehicle's electrical system to negative earth or find a fuel pump specifically designed for positive earth applications, as using a negative earth pump on a positive earth system will cause it to malfunction or be damaged.

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