Fuel Pump Regulator: Installing With A Return Line

Installing a fuel pump regulator with a return line can be a tricky task. The process involves plumbing a bypass regulator before the carburetor, which allows for unrestricted fuel flow while also regulating pressure and returning unused fuel to the gas tank. The choice of regulator location is important, as it can affect ease of installation, adjustment, and appearance. The longer the fuel line, the greater the potential for fuel pressure loss, so getting the regulator close to its destination is often recommended. However, some applications may prioritize convenience or aesthetics when choosing the location. The type of regulator used is also a key consideration, with deadhead-style and bypass-style regulators being popular options, each with its own advantages and disadvantages.

Bypass vs. deadhead-style regulators

Bypass and deadhead-style regulators are two types of fuel pressure regulators. A deadhead-style regulator is a simple and popular regulator set-up that is placed between the fuel pump and the carburetor. It uses a restriction to lower fuel pressure by decreasing fuel flow with the help of a diaphragm and seat, and it uses a spring to provide pressure adjustability. Deadhead regulators do not use a return line, which decreases installation costs but may limit performance capabilities. They are typically used to regulate fuel pressures in the 1-9 psi range.

On the other hand, a bypass regulator is plumbed before the carburetor, which allows for higher pressure in the feed line to counteract the high g-forces during rapid acceleration. This type of regulator allows fuel to flow unrestricted to the carburetor while still regulating pressure and returning unused fuel to the gas tank. This helps to prevent vapor lock and reduces the overall amperage needed to run the fuel pump.

One of the main differences between the two styles is that a deadhead regulator does not use a return line, while a bypass regulator does. This means that with a deadhead regulator, there is no fuel redirected back to the fuel tank, which can increase the temperature of the fuel and the chance of vapor lock. A bypass regulator, on the other hand, bleeds off excess fuel pressure and returns it to the fuel tank, keeping the fuel cooler and reducing the load on the fuel pump.

Another difference is that a deadhead regulator controls fuel pressure by restricting fuel flow between the pump and the regulator, which places additional load on the fuel system. This can lead to issues such as fluctuating fuel pressure, pressure creep, and potential engine flooding. In contrast, a bypass regulator provides a steadier fuel supply, resulting in a smoother and more stable fuel pressure curve.

When deciding between a bypass and a deadhead-style regulator, it is important to consider the specific requirements of your vehicle and engine. While a deadhead regulator is a simpler and more cost-effective option, a bypass regulator offers improved performance and fuel pressure regulation, especially for high-performance engines or drag racing applications.

Return line placement

The placement of the return line is a crucial aspect of installing a fuel pump regulator with a return line. Here are some detailed instructions and considerations for the return line placement:

The return line is an essential component of a fuel pump regulator, allowing unused fuel to be returned to the fuel tank. This helps prevent issues such as fluctuating fuel pressure, pressure creep, and vapour lock. It is important to note that the return line placement can vary depending on the vehicle and regulator type.

For a bypass regulator, it is recommended to place the regulator on the return line side of the fuel log. This setup allows unrestricted fuel flow to the carburetor while still regulating pressure and returning unused fuel to the tank. This type of regulator is commonly used in street/strip applications and can help prevent vapour lock.

The return line placement can also depend on the fuel system's performance and application. For systems with lower power or those not subjected to high g-forces, the regulator can be placed further from the fuel destination (fuel rail, carburetor, or injection pump) without causing significant pressure loss. However, for high-performance applications or drag racing vehicles, it is recommended to place the regulator closer to the fuel destination to minimize pressure loss during high-demand situations.

Additionally, the return line placement should consider ease of installation, adjustment, and appearance. Some individuals may prefer to mount the regulator in a convenient and accessible location, while others may opt for a more discreet placement to achieve a cleaner look.

It is worth noting that aftermarket fuel pressure regulators should be installed after the rails to avoid consuming all the fuel before it reaches the rear of the rail. This setup ensures that any unused fuel is returned to the tank.

Regulating fuel pressure

There are different styles of regulators, each with its advantages. The deadhead-style regulator, for example, is one of the simplest and most popular. It is placed between the fuel pump and the carburetor and uses a restriction to lower fuel pressure by decreasing fuel flow. This style does not use a return line, which can decrease installation costs but may limit performance capabilities. On the other hand, a bypass-style regulator can help alleviate issues caused by overworking a deadhead regulator, such as fluctuating fuel pressure or pressure creep, by bleeding off excess fuel pressure and returning it to the fuel tank.

When installing a fuel pressure regulator, it is important to consider the placement. Some sources suggest that the regulator should be placed before the carburetor to regulate the pressure going into it, while others argue that it should be placed after the carburetor, on the return side, to ensure that the fuel rail has priority in fuel flow. It is also important to note that the regulator can be placed anywhere in the system, and it will still regulate fuel pressure. Additionally, the type of system you have, whether it be a factory returnless system or a typical return-style system, will determine the placement of the regulator. In a returnless system, the regulator is in the tank next to the fuel pump, while in a return-style system, it is typically placed after the rail.

To regulate fuel pressure effectively, you can adjust the base pressure on the FPR via an adjustment screw to suit the injectors and fuel pump system you are using. This allows for fine-tuning to achieve the perfect balance and fuel efficiency, making it indispensable for high-performance machines. Furthermore, by plumbing a bypass regulator, drag racers can build higher pressure in the feed to counteract high g-forces experienced during rapid acceleration. This, in turn, helps reduce the overall amperage needed to run the fuel pump.

Fuel pump location

The location of the fuel pump is an important consideration when installing a fuel pump regulator with a return line. The regulator's location can impact fuel pressure, ease of installation, and the overall appearance of the setup.

There are differing opinions on whether the regulator should be placed close to or further away from the fuel's destination (fuel rail, fuel log, carburetor, or injection pump). Some people believe that placing the regulator close to the fuel's destination can improve fuel pressure regulation, especially in high-power applications or when the vehicle is subjected to high g-force launches. The longer the fuel line, the greater the potential for fuel pressure loss. Therefore, placing the regulator closer to the fuel's destination can help mitigate this issue.

On the other hand, others argue that it is also acceptable to place the regulator further away, even at the opposite end of the vehicle. This decision may be influenced by factors such as ease of installation, accessibility for adjustments, and achieving a cleaner, more aesthetically pleasing setup.

It is recommended to research your specific fuel pump and obtain information such as flow rate, maximum working pressure, and amperage draw to make an informed decision about the regulator's location. Additionally, consider the type of fuel delivery system and whether the application is subject to high g-forces or requires highly accurate pressure regulation.

For example, in a street/strip application, it is suggested to run the feed line directly to the carburetor's fuel log and then place the regulator on the return line side. This allows unrestricted fuel flow to the carburetor while still regulating pressure and returning unused fuel to the tank.

Advantages of a return-style system

A return-style system offers several advantages over a returnless fuel system. Here are some benefits of installing a fuel pump regulator with a return line:

Consistent Fuel Supply and Pressure

A return-style system ensures a consistent fuel supply and pressure. The regulator, placed after the carburetor, controls the fuel pressure going into the carburetor, allowing for equal pressure to both float bowls. This setup prevents issues like fluctuating fuel pressure and pressure creep, which can occur with a dead-head style regulator.

Vapor Lock Mitigation

The constant cycling of fuel back into the tank in a return-style system helps to cool the gasoline, mitigating vapor lock issues. This is particularly beneficial for engines with poor venting/airflow and high ambient underhood temperatures, as the fuel temperatures are more consistent.

Easier Engine Tuning

The more consistent fuel temperatures in a return-style system make engine tuning easier. Additionally, the fuel pressure is more stable at the carburetor or injectors because the regulator can be placed closer to the delivery point.

Fuel Efficiency

A return-style system can improve fuel efficiency by returning unused fuel back to the tank. This prevents fuel from being wasted, as it circulates continuously in the system.

Reduced Amperage Requirements

The use of a bypass regulator in a return-style system helps reduce the overall amperage required to run the fuel pump. This is because the fuel is always circulating, and the regulator controls the pressure, ensuring a consistent fuel supply.

While a return-style system offers these advantages, it's important to consider potential drawbacks, such as the constant operation of the fuel pump, which may shorten its lifespan, and the increased complexity of the plumbing system due to the separate return line.

Frequently asked questions