Gravity Micro Electric: Increasing Fuel Pressure With Innovation

Mr. Gasket offers a micro-electric fuel pump (model 12S) with 2-3.5 PSI that can be used to increase fuel pressure. This pump is designed for use with small air-cooled engines and has a simple two-wire design, working with 12-volt negative ground systems. It includes fittings and mounting hardware, as well as easy-to-follow DIY instructions, making it a popular choice for those seeking a fuel transfer pump that eliminates vapor lock and flooding issues. The pump's performance and ease of installation have received positive feedback from customers, although some have reported reliability issues.

The PSI of a gravity-fed fuel system on a small air-cooled engine

One response to the forum post states that at sea level, atmospheric pressure is approximately 15 PSI, and that 3.5 PSI would likely not be too much for a small carburetor. However, they note that a bypass system would be needed so that surplus fuel could return to the fuel tank. Another forum user provides a "rule of thumb" that each foot of elevation between the tank and carburetor will produce 0.5 PSI of fuel pressure.

The original poster then clarifies that they are feeding 7 small engines from a single tank positioned about 18" lower than the engines. They mention that Mr. Gasket offers a "micro-electric" fuel pump (model 12S) with a 2-3.5 PSI rating. Another user responds that the position of the fuel tank relative to the engines will likely not have a noticeable effect on the electric fuel pump. They suggest locating the fuel pump at the bottom of the fuel tank to avoid priming issues.

The forum discussion also touches on the topic of testing and regulating the fuel pressure. One user suggests hooking up a temporary tank raised six feet above the carburetor to see if 3 PSI is sufficient. Another user mentions that the Tecumseh manual recommends applying 5 PSI to the fuel inlet of the carburetor and ensuring that it does not drop below 1.5 PSI in one minute.

In terms of specific products, Mr. Gasket offers a micro-electric fuel pump (model 12S) that can provide 2-3.5 PSI. This pump is designed for use with gasoline and has a gravity-fed type pump with a simple two-wire design. It works on 12-volt negative ground systems and includes fittings, mounting hardware, and a 100-micron inline filter.

In summary, the PSI of a gravity-fed fuel system on a small air-cooled engine can vary depending on factors such as the height difference between the fuel tank and carburetor, atmospheric pressure, and the specific engine configuration. While there is no definitive answer to the original question, the forum discussion provides insights and suggestions for determining and regulating the fuel pressure in such a system.

The impact of altitude on fuel pressure

Altitude has a significant impact on fuel pressure and consumption. Engines of new passenger cars are typically tuned to operate at sea level, but in many countries, a significant portion of engine operation occurs at higher altitudes. The change in air density and vehicle aerodynamics at these higher altitudes can lead to lower or higher fuel consumption, depending on various factors.

At higher altitudes, the lower air density results in a wider throttle opening, leading to decreased throttle friction and lower fuel consumption in gasoline engines. However, the vehicle's deceleration times increase due to the change in aerodynamics, which can also impact fuel consumption. The specific impact of altitude on fuel consumption can vary depending on the type of driving cycle and other factors such as temperature, road conditions, and traffic conditions.

In the case of gravity micro-electric fuel systems, the impact of altitude on fuel pressure is influenced by several factors, including the height of the fuel tank relative to the engine and the specific characteristics of the fuel pump. According to a user on SmokStak, a general rule of thumb is that for each foot of elevation between the tank and the carburetor, there is a corresponding 0.5 psi of fuel pressure. Additionally, the user suggests that a micro-electric fuel pump with 2-3.5 PSI would not be too much pressure for a small carburetor, but a bypass system may be necessary to return excess fuel to the tank.

Another user on SmokStak mentions that the position of the fuel tank may not have a noticeable effect on the electric fuel pump's performance, but it is recommended to locate the pump at the bottom of the fuel tank to avoid priming issues. The same user also suggests running a temporary setup with the fuel tank raised to test the impact of altitude on fuel pressure and determine if any adjustments are needed.

Overall, the impact of altitude on fuel pressure and consumption can be complex and depend on a variety of factors, including the type of engine, the altitude of operation, and the specific characteristics of the fuel system and pump.

The role of a bypass system in managing surplus fuel

Bypass systems are an essential component in managing surplus fuel in gravity micro-electric fuel setups. When using a micro-electric fuel pump, such as the Mr. Gasket model with a 2-3.5 PSI rating, a bypass system ensures that excess fuel can return to the fuel tank. This is particularly important when dealing with small engines and carburetor systems, as too much pressure can lead to flooding and other issues.

The role of a bypass system is to regulate and control the fuel pressure, preventing it from exceeding the desired level. In a return-style or bypass-style regulator, fuel enters through the inlet port and passes through a fuel bypass valve and fuel return line port, which govern the fuel flow and pressure. This type of regulator features a return line that allows any excess pressure to be bled off through the return port, ensuring a constant and effective fuel pressure at the outlet port.

The advantages of a bypass system are significant. Firstly, it provides constant and effective fuel pressure, enabling more accurate fuel pressure settings. Secondly, it prolongs pump life and reduces pump operation noise, as the pump only works hard enough to maintain the desired pressure.

However, there are also some drawbacks to consider. Bypass systems can add complexity and cost due to the additional fuel lines and fittings required. The return line is also sensitive to pressure drops, requiring larger return lines with limited bends and a direct return to unpressurized tanks or reservoirs.

Overall, a bypass system plays a crucial role in managing surplus fuel in gravity micro-electric setups by allowing excess fuel to return to the tank and maintaining optimal fuel pressure. While there are benefits to this system, it is important to carefully consider the potential drawbacks and ensure that the setup is properly configured to handle the specific engine and carburetor requirements.

The placement of the fuel pump to avoid priming issues

To avoid priming issues, it is recommended to locate the fuel pump at the bottom of the fuel tank. This placement ensures that the pump can draw fuel more easily and prevents air bubbles or pockets from forming, which can cause issues with fuel delivery and engine operation.

When placing the fuel pump at the bottom of the tank, it is important to ensure that the pump is securely mounted and that all necessary fittings and hardware are included. This may include items such as mounting brackets, hoses, or tubing to connect the pump to the fuel tank and engine.

Additionally, when working with fuel, it is crucial to take the necessary safety precautions. This includes working in a well-ventilated area, wearing appropriate protective gear, and ensuring that there are no sources of ignition nearby. It is also important to disconnect the battery before beginning any work on the fuel system, as this can help prevent electrical damage and reduce the risk of accidental ignition.

By locating the fuel pump at the bottom of the fuel tank and following the necessary safety procedures, you can help avoid priming issues and ensure the smooth operation of your engine.

The compatibility of a micro-electric fuel pump with a specific engine

Engine Fuel System Design:

• The micro-electric fuel pump should be compatible with the engine's fuel system, which can be either gravity-fed or pressure-fed.
• For gravity-fed systems, ensure the pump can provide sufficient pressure to overcome the height difference between the fuel tank and the engine.
• For pressure-fed systems, match the pump's pressure and flow rate to the engine's requirements.

Pressure and Flow Rate:

• Micro-electric fuel pumps typically have a pressure range of 4-7 PSI, which is suitable for most carbureted engines.
• Ensure the pump's flow rate (measured in gallons per hour, GPH) meets the engine's fuel requirements.

Vehicle Voltage System:

Micro-electric fuel pumps usually operate on 12-volt negative ground systems. Ensure your vehicle's electrical system matches this requirement.

When installing a micro-electric fuel pump, it is crucial to follow the manufacturer's instructions and consider factors such as pump mounting location, fuel line connections, and any necessary fuel pressure regulation. Proper installation and compatibility will ensure optimal engine performance and fuel delivery.

Frequently asked questions