Fuel Pressure Requirements For Fitech Systems: How Much Is Enough?

how much fuel pressure does fitech need

The fuel pressure required by the FiTech EFI system is a topic of discussion among car enthusiasts and mechanics. While some sources suggest that the system operates at a fuel pressure of 58 lbs, others recommend slightly lower or higher pressures for optimal performance. Adjusting the fuel pressure can impact the air-fuel ratio, with higher pressure potentially leading to a leaner mixture and lower pressure resulting in a richer mixture. It is important to fine-tune the fuel pressure to ensure the engine runs efficiently and avoid potential issues such as hesitation or bogging.

Characteristics Values
Fuel Pressure 58 lbs

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Fuel pressure requirements vary depending on the type of engine and fuel system. For example, carbureted engines typically operate within a fuel pressure range of 4-7.5 psi, while fuel-injected engines require higher pressures, usually between 35-65 psi.

In the context of FiTech, a fuel pressure of 58 lbs is often referenced as the standard or recommended level. However, it is important to distinguish between the minimum required fuel pressure and the optimal or recommended level. A fuel pressure of 58 lbs falls within the typical range for fuel-injected engines, and it is recommended by some users and sources as the optimal setting for certain FiTech applications.

In a forum post, a user with the username "Poncho" states that the FiTech system they are using runs on 58 lbs of fuel pressure. They question whether this is the minimum required pressure or the recommended level, as they are observing approximate fuel pressure readings of 54 lbs at idle, which may be causing a lean condition.

In response, another user suggests that the recommended fuel pressure for the FiTech system is indeed 58 lbs, and that the user's fuel pump should be capable of delivering well above this pressure at full power. They advise checking the fuel pump setup, including the wiring, grounding, and return line connections, to ensure it is configured correctly.

It is worth noting that fuel pressure requirements can vary depending on the specific application and engine specifications. For example, in another forum post, a user installing a Pro Flo 4 system on an AMC 304 engine mentions that the specs call for a fuel pressure of 43 psi, while their FiTech mini fuel sump is set at 58 psi. In this case, a regulator may be required to compensate for the difference in fuel pressure requirements.

To summarize, a fuel pressure of 58 lbs is recommended by some users and sources for certain FiTech applications. However, it is important to consult the specific requirements for your engine and fuel system, as fuel pressure requirements can vary depending on various factors, including the type of engine, fuel injection system, and horsepower.

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High AFR readings: is it due to an exhaust leak?

The FiTech EFI system is reported to run on 58 lbs of fuel pressure. However, some users have experienced issues with high AFR readings, which can be caused by various factors, including exhaust leaks.

High AFR readings can be caused by an exhaust leak, which introduces ambient air into the exhaust stream, increasing the amount of oxygen present. This can lead the sensor to interpret the condition as lean, indicating that there was not enough fuel present during combustion. Even a small exhaust leak can distort the AFR readings, providing inaccurate tuning information. Inaccurate AFR readings at idle and cruise situations can be particularly problematic, as the engine spends the majority of its time in these zones.

To diagnose an exhaust leak, it is recommended to check the pipes for any signs of pollution or damage. This can include gasket failures, loose fasteners, or pinhole leaks in the header tubes. Gasket failures at the exhaust collector or header/exhaust manifold flange can significantly impact AFR readings, rendering them useless. Pinhole leaks at idle and cruise can also affect AFR readings, tricking the ECU into adding supplemental fuel.

In addition to exhaust leaks, other factors that can contribute to high AFR readings include fuel pressure, fuel pump issues, and installation problems. It is important to ensure that the fuel pressure is within the recommended range and that the fuel pump and relay are functioning correctly. Installation issues, such as incorrect fuel line connections or a missing return line, can also impact fuel pressure and AFR readings.

When troubleshooting high AFR readings, it is recommended to perform a datalog and send it to FiTech for further analysis. It may also be helpful to check fuel trims at idle to ensure that the ECU is not adding too much fuel, which can be indicated by a check engine light.

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Lambda readings: how to get them to the target?

The FiTech EFI system can run on fuel pressures of around 58 lbs, though some users have reported achieving only slightly lower pressures of around 54 lbs at idle.

Now, onto Lambda readings and how to get them to the target. Lambda readings are important as they indicate the air-fuel ratio (AFR) in your engine, which ideally should be at a stoichiometric ratio of 14.7:1 for optimal combustion. Here are some steps and tips to help you achieve your target Lambda readings:

  • Understand the Basics: Lambda is a measure of the air-fuel ratio, with Lambda 1 representing the stoichiometric ratio of 14.7:1. A Lambda reading below 1 indicates a rich mixture (excess fuel), while a reading above 1 indicates a lean mixture (excess air).
  • Choose an Appropriate Starting Point: For naturally aspirated engines, a Lambda target of 0.88 to 0.90 is generally safe and close to optimal. Starting with this range can help you fine-tune your engine's performance without risking going too far off the ideal ratio.
  • Monitor Lambda Readings During a Full-Power Run: When tuning your engine, pay close attention to Lambda readings during a full-power run. If your Lambda reading is greater than your target (indicating a lean mixture), you need to adjust the fuel table to increase the fuel ratio to hit your target.
  • Fine-Tune with Test Runs: After tuning the fuel table to achieve your target Lambda at all RPMs, conduct test runs with slightly richer and leaner mixtures to optimize performance and engine safety. For example, you can try a target Lambda of 0.83 to see if it makes more power or maintains power while reducing coolant temperature rise.
  • Consider Coolant Temperatures: Repeat the test runs with the coolant temperature at the maximum end of the normal range to ensure that there are no indications of knock, as knock becomes more common at higher combustion temperatures.
  • Use a Wideband Oxygen Sensor: Install a wideband oxygen sensor in your FiTech EFI system to directly measure the Lambda value in the exhaust system. This provides an accurate reading of the air-fuel ratio, allowing you to make more precise adjustments.
  • Utilize the FiTech ECU: The FiTech ECU can sense the Lambda value and convert it to an approximate AFR. It uses this information for fuel trim, which quickly adjusts the injected pulse width to achieve the target AFR. The ECU also has fuel learning capabilities, adapting to consistent fuel trim adjustments and saving them in its memory.
  • Adjust Fuel Trim Settings: Play around with the fuel trim settings in the FiTech ECU, such as Fuel Trim Max and Min, to fine-tune the amount of extra fuel that can be added or removed by the fuel trim function.
  • Consider Engine Temperature: Keep in mind that engine temperature significantly affects fuel requirements. Colder engines require more fuel, and the fuel wall film needs to be applied, while warm engines have thinner oil and don't need as much fuel to achieve combustion.
  • Fine-Tune for Transient Events: Transient events, such as quick throttle tip-ins, may require adjustments to the acceleration fuel calculation. Fine-tune settings like "Accel Pump" and "Fast Accel" to ensure enough fuel is added during these transient events.
  • Monitor AFR Table: The AFR table is a 3x3 matrix that interpolates the AFR based on breakpoints. Ensure that your engine operates within the desired AFR range by setting the appropriate breakpoints for different RPMs and manifold pressures.

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Stealth 360 pump: what's the ideal PWM setting?

The ideal PWM setting for a Stealth 360 pump will depend on the application and the desired level of noise. Some people prefer to set their pump to a static speed, while others prefer to vary the speed based on factors such as loop temperature, CPU temperature, or coolant temperature.

If you are looking for a quiet setup, you may want to set the PWM to a lower percentage, such as 20-50%. This will reduce the noise from the pump but may also impact the flow rate. You can also try to find the pump rpm that is just below the level where it becomes audible and set that as your minimum speed.

On the other hand, if performance is your priority, you may want to set the PWM to a higher percentage or even 100%. This will increase the flow rate and improve cooling but will also make the pump louder.

It's worth noting that the Stealth 360 pump may not be able to reach the recommended fuel pressure for FiTech, which is around 58 lbs. Some users have reported that even at 100% PWM, their fuel pressure was lower than expected. Therefore, you may need to consider other factors such as fuel line size, fuel filters, and return lines to achieve the desired fuel pressure.

Additionally, it's important to ensure that your fuel pressure gauge is accurate and that your pump is properly grounded and connected. If you are still experiencing issues with fuel pressure or pump performance, you may need to consult with a mechanic or a specialist in fuel injection systems.

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Fuel delivery and regulators: what's the role of the return line?

Fuel delivery and regulators play a crucial role in ensuring the proper functioning of a vehicle's fuel system, which is responsible for storing, controlling, and supplying fuel to the engine's combustion chamber. The fuel system comprises the fuel tank, fuel pump, fuel lines, fuel filters, and fuel injectors. One key component in this system is the fuel return line, which has an important role in ensuring the efficient and safe operation of the engine.

The fuel return line is a hose that serves a critical function in vehicles equipped with return-type fuel systems. Its primary role is to route excess fuel from the engine back to the fuel tank, where a fuel pressure regulator is typically located. This process helps maintain consistent fuel pressure and flow, ensuring that the injectors receive the correct amount of fuel.

In a return-type fuel system, the fuel pressure regulator plays a pivotal role in managing fuel pressure. It achieves this by diverging fuel pressure based on the power of the vacuum suction from the engine's intake system. This regulation ensures that the fuel pressure and flow remain equal and consistent when the fuel reaches the injectors. As a result, the engine receives the precise amount of fuel it requires for optimal performance.

However, it is worth noting that not all fuel injection systems have return lines. For instance, carburetor vehicles typically do not have fuel return lines unless the carburetor is fed by an electric fuel pump. In cases where a carburetor has a return line, it can still function without it due to the relatively weak electric pump.

The presence or absence of a return line can have implications for fuel temperature. In return-type fuel systems, the fuel returning to the tank is typically hotter, which can affect the fuel's combustibility and the vehicle's overall efficiency. On the other hand, returnless fuel delivery systems allow the fuel to remain colder, resulting in improved fuel economy and reduced emissions.

Frequently asked questions

FiTech runs on 58 lbs of fuel pressure.

The minimum fuel pressure required by FiTech is unknown, but it is recommended to run it on 58 lbs of fuel pressure.

If the fuel pressure is too low, it can cause a lean condition at idle, resulting in high AFR readings.

You can try adjusting the throttle adjustment screw, checking for exhaust leaks, or using a different fuel pressure gauge.

It is recommended to use a brand new fuel pressure gauge to ensure accuracy.

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