Selecting The Right Carb Fuel Pump Pressure Regulator

Choosing the right fuel pressure regulator for your vehicle is essential to ensure optimal performance and fuel efficiency. There are several types of fuel pressure regulators available on the market, each with its own advantages and disadvantages. This article will discuss the two most common types of fuel pressure regulators: deadhead regulators and bypass regulators, and provide guidance on selecting the most suitable option for your carbureted engine.

Deadhead vs bypass regulators

Deadhead and bypass regulators are both types of fuel pressure regulators. A fuel pressure regulator is a critical piece of equipment that should be matched to the type of fuel delivery system and fuel pump being used.

A deadhead regulator is a simple and popular setup, often used with carbureted engines. It is placed between the fuel pump and the carburetor, and uses a restriction to lower fuel pressure by decreasing fuel flow. This is achieved through the use of a diaphragm and seat that restricts fuel flow, with a spring providing pressure adjustability. Deadhead regulators do not use a return line, which helps to decrease installation costs but can limit performance capabilities. They typically regulate fuel pressures in the 1-9 psi range and are perfect for use with most low-pressure mechanical and some electric fuel pumps.

A bypass regulator, on the other hand, bleeds off excess fuel pressure and returns it directly to the fuel tank via a return line. This helps to eliminate pressure creep, lower fuel temperatures, and provide a more stable pressure curve. It can also react much quicker to sudden fuel flow changes, correcting a potential lean condition. A bypass regulator is more complex and expensive to install due to the need for a return line, but it offers improved performance and reliability. It is better suited to high-performance engines with higher fuel flow demands, as it can maintain steady fuel pressure and prevent issues such as engine flooding and vapor lock.

In summary, a deadhead regulator is a simpler and more cost-effective option, but it may not be suitable for high-performance engines. A bypass regulator offers improved performance and reliability by maintaining steady fuel pressure and temperature, but it is more complex and expensive to install. The choice between the two depends on the specific requirements and constraints of the engine and fuel system in question.

Regulator installation

Before installing a fuel pressure regulator, it is important to do some research on your fuel pump to understand its flow, maximum working pressure, and amperage draw. This will help you choose the right regulator for your fuel pump.

If you have a carbureted engine, you will likely be using a deadhead-style regulator, which is placed between the fuel pump and the carburetor. This type of regulator uses a diaphragm and seat to restrict fuel flow and decrease fuel pressure. Deadhead regulators do not use a return line, which can lower installation costs but may limit performance.

Alternatively, you may choose to install a bypass-style regulator, which can help improve performance and reliability. Unlike deadhead regulators, bypass regulators bleed off excess fuel pressure and return it to the fuel tank via a return line. This helps to eliminate pressure creep, lower fuel temperatures, and provide a more stable pressure curve. Bypass regulators can also react more quickly to sudden changes in fuel flow, helping to prevent lean spikes and keep the fuel bowls full.

When installing a fuel pressure regulator, it is important to position it as close to the carburetor as possible to ensure that the fuel line fills back up with fuel quickly after changes in engine load. Additionally, the regulator should be mounted in a location that minimises exposure to heat sources and avoids interference with the vehicle's body and chassis movement.

If you are installing an electric fuel pump, the pump should be mounted on the chassis in a vertical position with the pump motor on top. The inlet and outlet of the pump must be mounted below the lowest point of the tank to ensure an adequate fuel supply. The pump should also be kept away from hot areas such as the exhaust and should not be mounted in a closed area like the vehicle's trunk.

For high-pressure electric fuel pumps, a pressure regulator must be installed in the line between the pump and the carburetor. The regulator should be positioned as close to the carburetor as possible and should not be mounted on any extremely hot surfaces. The regulator's pressure can be adjusted by loosening the regulator locknut and turning the adjustment screw—turning it clockwise increases the pressure, while turning it counter-clockwise decreases the pressure.

Regulator maintenance

A fuel pressure regulator is a critical piece of equipment that ensures the correct fuel pressure at the carburettor or injectors. It is important to perform regular maintenance on your fuel pressure regulator to ensure it is functioning correctly and to prolong its lifespan. Here are some tips to maintain your fuel pressure regulator:

• Research your fuel pump: Before installing a fuel pressure regulator, it is important to research your fuel pump and obtain basic information such as flow rate, maximum working pressure, and amperage draw. This will help you choose the correct regulator for your system.
• Check for leaks: Over time, the diaphragm in the regulator may crack or split, causing fuel to leak out. If you notice any leaks, replace the diaphragm and spring with a repair kit.
• Monitor fuel pressure: Keep an eye on your fuel pressure gauge to ensure it is within the correct range for your regulator. If the pressure is too high or too low, it may indicate an issue with the regulator.
• Clean or replace the fuel filter: A clogged or restrictive fuel filter can cause the regulator to work harder, leading to increased wear and tear. Regularly clean or replace the fuel filter to ensure optimal fuel flow.
• Inspect the return line: For return-style regulators, ensure the return line is the correct size and free from restrictions. An undersized or kinked return line can cause backpressure and affect the regulator's performance.
• Adjust the pressure: Most aftermarket regulators are adjustable. Ensure the pressure is set correctly for your engine's requirements, especially after installation or maintenance.
• Bypass regulator maintenance: If using a bypass regulator, ensure the return line is clear and free from restrictions. Also, check the diaphragm and spring for any signs of wear or damage.
• Lubricate moving parts: Some regulators may have moving parts that require lubrication. Consult your regulator's manual for specific lubrication requirements and recommended intervals.
• Check for corrosion: Inspect the regulator for any signs of corrosion or damage, especially if it is exposed to moisture or harsh environments.
• Follow manufacturer recommendations: Each regulator may have specific maintenance requirements or intervals. Refer to the manufacturer's instructions or manual for detailed maintenance procedures.

By following these maintenance tips, you can help ensure your fuel pressure regulator is functioning correctly and prolong its lifespan, leading to a more reliable and efficient fuel system.

Fuel pump and regulator compatibility

Most lever-style mechanical fuel pumps do not require a regulator, and some electric fuel pumps have a regulator built into them. These pumps are typically low-pressure units designed for use with carburetors only.

If your fuel pump requires an external regulator, there are a few options to consider. One popular option is the deadhead-style regulator, which is commonly used with carbureted engines. This style of regulator is placed between the fuel pump and the carburetor and uses a restriction to lower fuel pressure by decreasing fuel flow. Deadhead regulators do not use a return line, which can help reduce installation costs but may limit performance capabilities. They typically regulate fuel pressures in the 1-9 psi range and are suitable for use with most low-pressure mechanical and some electric fuel pumps. However, they may struggle to meet the fuel flow demands of high-performance engines, leading to issues such as fluctuating fuel pressure, pressure creep, and the possibility of flooding the engine.

Another option is a bypass-style regulator, which can help alleviate the issues associated with deadhead regulators by bleeding off excess fuel pressure and returning it to the fuel tank. This design helps eliminate pressure creep, lowers fuel temperatures, and provides a more stable pressure curve. Bypass regulators are also able to react more quickly to sudden fuel flow changes, making them a good choice for drag racing applications. It is important to note that bypass regulators are not just for fuel injection systems; they can also be beneficial for carbureted systems by providing a more consistent fuel supply and reducing fuel temperatures.

When choosing a fuel pressure regulator, it is important to consider factors such as the flow, maximum working pressure, and amperage draw of the fuel pump. Taking the time to plan out the fuel system and match quality components will ensure safe and reliable fuel system performance.

Advantages and disadvantages of different regulator types

There are two main types of fuel pressure regulators: return style (or bypass) and deadhead (or blocking regulators).

Return-style regulators stabilise fuel pressure and direct excess fuel back to the tank. They are adjustable, allowing users to fine-tune the fuel pressure to match their engine's requirements. They are particularly useful in EFI systems and setups with carburetors used in conjunction with high-pressure fuel pumps. They are also beneficial for turbocharged or supercharged engines, as they ensure a more consistent fuel pressure, optimising engine performance. However, the main drawback of return-style regulators is their complexity. They require a return line back to the fuel tank, which complicates the installation process.

Deadhead regulators, on the other hand, do not have a return line. They regulate fuel pressure by restricting fuel flow once it reaches a predetermined level. Deadhead regulators are simpler in design and are less expensive to build and maintain due to fewer components and connections. They are well-suited for less demanding applications, such as classic cars with carbureted engines used for regular driving. However, deadhead regulators can cause fuel temperatures to rise due to the restriction they create in the fuel flow. This restriction can lead to increased fuel pressure upstream of the regulator, resulting in a rise in fuel temperature. Additionally, deadhead regulators cannot be used for most EFI systems, and they may be hard on the fuel pump as increased pressure is needed to close the valve.

A third type of regulator, the bypass regulator, is also available. Bypass regulators bleed off excess fuel pressure, dumping it into a return line and recirculating it back into the tank. This design helps eliminate pressure creep, lower fuel temperatures, and provide a more stable pressure curve. Bypass regulators are particularly beneficial for high-performance engines, as they can handle the increased fuel flow demands and help maintain steady fuel pressure. They are also useful for drag racing, as they can build higher pressure in the feed to counteract the high g-forces during launches and rapid acceleration.

Frequently asked questions