Adjusting Fi Tech Fuel Pressure: The Ultimate Guide

Adjusting fuel pressure is an important aspect of maintaining optimal engine performance. Fuel pressure refers to the force exerted by the fuel pump to deliver fuel from the tank to the engine. The FiTech EFI system, a popular fuel injection setup, has specific fuel pressure requirements for efficient operation. Users have reported varying fuel pressure readings, with some experiencing lean conditions at idle and others making adjustments to the fuel pump control settings. It is recommended to have a return line and ensure proper fuel line connections to the FiTech system. The fuel pump should be able to deliver sufficient fuel pressure, and adjustments can be made through the FiTech Command Center or handheld controller to fine-tune fuel delivery and engine performance.

Fuel delivery and regulators

The fuel delivery and regulators are key components of the FiTech fuel injection system. The system is designed to deliver a consistent and appropriate amount of fuel to the engine, ensuring optimal performance and fuel efficiency.

The fuel delivery process begins with the fuel pump, which is controlled by the FiTech ECU. The ECU can drive the fuel pump directly, eliminating the need for an external relay. This allows for PWM (pulse width modulation) control, where the voltage can be adjusted based on fuel demand. At idle and light cruise, the voltage can be reduced, as less fuel is needed.

The FiTech system recommends a fuel pressure of 58 lbs. However, it is important to note that this value may vary depending on specific engine configurations and requirements. Some users have reported fuel pressure readings of around 54 lbs at idle, which can result in a lean condition. To address this, it is suggested to check the fuel pressure gauge and ensure the return line is connected correctly.

The fuel pump settings can be adjusted using the Handheld Controller. Parameters such as "Pump Prime Time," "TPS for PUMP ON," "RPM for PUMP ON," and "PWM Low Flow" can be modified to fine-tune fuel delivery. These settings control the duration of pump operation, the throttle position, engine speed, and fuel flow rate, respectively.

Additionally, the FiTech system employs fuel learning capabilities, where it can adjust the fuel injection based on sensor signals and target AFR (Air Fuel Ratio). The system can increase or decrease the injected fuel to achieve the desired AFR, ensuring the engine receives the correct amount of fuel. This closed-loop fuel control system adapts to the engine's needs and provides a more efficient and responsive fuel delivery.

It is important to note that fuel pressure and delivery play a crucial role in the overall performance of the engine. Ensuring proper fuel pressure, adjusting the fuel pump settings, and utilising the fuel learning capabilities of the FiTech system can help optimise fuel delivery and enhance the engine's performance.

Fuel pump control

The FiTech ECU for Go EFI systems has a special driver circuit that will drive the fuel pump directly, which means that an external relay is not needed. This driver circuit allows both PWM control (pulse width modulated) and direct internal relay drive of the fuel pump. This allows the voltage to be reduced when the fuel demand is low, such as at idle and light cruise.

The Fuel Pump Control menu in the Go-EFI PRO Tuning settings includes the following:

• Pump Prime Time: 5.0
• Flow for Pump On: 75.0
• MAP for Pump On: 95.0
• TPS for Pump On: 25.5/30.0
• RPM for Pump On: 3000/4500
• Volts for Pump On: 9.0
• PWM Low Flow: 40.8/45%
• PWM Mid Flow: 89.8
• PWM High Flow: 97.6

The PWM (pulse-width modulation) reading at "normal" cruise speeds/RPM appears to be between 40% and 45%. At WOT (wide-open throttle), the pump should be at 100% PWM.

One user reported that they were able to reduce the heat buildup in their FCC (Fuel Command Center) by modifying it to a pass-through system, which involves removing the float and vent filter. This allows the FCC to act as a surge tank, with fuel passing from the low-pressure side to the vent and returning to the gas tank. This modification is recommended for those experiencing issues with FCC heat, but it may result in fuel pressure loss and the need for a check valve.

Another user suggested restricting the return line to the tank to potentially reduce heat buildup.

Fuel pump relay

A fuel pump relay is an electronic component found on all vehicles with an internal combustion engine. Its function is to supply a consistent voltage to the fuel pump when the ignition is turned on. The fuel pump relay is usually controlled by the ignition or the power control module. When the ignition is turned on, the relay is activated and supplies electricity to the fuel pump, and when the ignition is shut off, the relay powers down the fuel pump.

The fuel pump relay can usually be found in the fuse box in the engine bay, which is typically a long black box that contains various fuses and relays. However, it can also be located in other places, such as under the hood, on the firewall, or near the steering column. If you cannot find it, it is recommended to check your owner's manual.

A faulty fuel pump relay can cause various issues, including:

• An engine that refuses to start, even though it may still crank when the key is turned due to a lack of power supplied to the fuel pump.
• An engine that suddenly stalls while running, indicating that the fuel pump relay has cut off power to the fuel pump.
• A sudden loss of power while driving or slowing down with no apparent reason, which may or may not lead to the car stalling.
• No noise coming from the fuel pump when the ignition is turned on, indicating that the fuel pump is not receiving power and is not operating.

If you suspect a problem with your fuel pump relay, it is recommended to perform a visual inspection and check for signs of corrosion and overheating. You can also use a digital multimeter to test the relay for continuity and check for shorted power pins.

Fuel pump pressure gauge

A fuel pump pressure gauge is a device used to measure the pressure of fuel in a vehicle's fuel system. It is an important tool for troubleshooting fuel system issues, such as a rough-running engine or decreased fuel efficiency.

There are many different types of fuel pump pressure gauges available on the market, each with its own unique features and specifications. Some gauges are designed to be used with specific types of vehicles, such as cars, trucks, motorcycles, or SUVs. It is important to select a gauge that is compatible with your vehicle's fuel system.

When using a fuel pump pressure gauge, it is important to ensure that it is properly connected to the fuel system. This may involve attaching the gauge to a Schrader valve test port or using an adapter if the vehicle does not have the correct valve. Additionally, it is crucial to follow safety precautions when working with fuel systems, as they can involve hazardous materials and high pressures.

In addition to the gauge itself, a fuel pump pressure gauge kit may include various adapters, fittings, hoses, and other tools to facilitate the connection to the fuel system and ensure accurate readings. It is recommended to refer to the vehicle's manual or seek professional assistance if you are unsure about the fuel system or the gauge installation process.

Fuel pump power

The FiTech ECU for Go EFI systems has a special driver circuit that will drive the fuel pump directly, meaning an external relay is not needed. This driver circuit allows both PWM control (pulse width modulated) and direct internal relay drive of the fuel pump. This allows the voltage to be reduced when the fuel demand is low, such as at idle and light cruise.

The fuel pump power can be adjusted in the 'Fuel Pump Control' menu. Here are the settings that can be adjusted:

• Pump Prime Time: At Key On, the pump is turned on for this much time, allowing the throttle body to be purged of air pockets and for the pressure to be built up to the normal operating pressure.
• Flow for Pump On: N/A
• MAP for Pump On: N/A
• TPS for Pump On: If the throttle is opened above this position, the internal relay is turned on to supply full power to the fuel pump.
• RPM for Pump On: If the RPM is above this speed, the internal relay is turned on to supply full power to the fuel pump.
• Volts for Pump On: N/A
• PWM Low Flow: When the fuel flow rate is low, and all of the other conditions for allowing PWM control to be met, this is the percentage of duty cycle that is used. Set this so that fuel pressure doesn't drop below the rated fuel pressure of the system.
• PWM Mid Flow: N/A
• PWM High Flow: N/A

It is important to note that the PWM settings are dependent on each other. For example, if you set the PWM Low Flow to 40, the PWM Mid Flow to 80, and the PWM High Flow to 100, the ECU will automatically adjust the fuel pump power based on the current flow rate. As the flow rate increases, the ECU will increase the power to the fuel pump, moving from 40% to 80% to 100% as the flow rate crosses the set thresholds.

Additionally, the fuel pump power can be affected by the return line setup. If a return line is not used, the fuel pump will always run at 100% power to maintain the required fuel pressure. However, if a return line is installed, the ECU can adjust the fuel pump power to maintain the desired fuel pressure, resulting in reduced heat buildup and improved fuel efficiency.

Frequently asked questions