Ezefi Fuel Pressure: Does It Hold After Shutoff?

The FAST EZ-EFI Fuel Injection System is a self-learning fuel injection system that has been praised by some for its performance and ease of installation, but criticized by others for its unreliability and poor customer support. One common issue with the system is that it can cause the engine to run rich, leading to spark plug fouling and poor fuel mileage. Some users have also reported hard starting, stalling, and rough idling issues. There have also been reports of the system not holding fuel pressure after shut-off, which can result in longer cranking times when starting the engine.

While there can be various causes for fuel pressure loss after shut-off, some potential reasons include a faulty fuel pressure regulator, leaky injectors, or a defective check valve in the fuel pump or system. It is important to note that some fuel systems are designed to hold pressure for a certain amount of time after shut-off, while others are not, so it is essential to refer to the specific system's specifications and characteristics.

Fuel pressure and exhaust leaks

Understanding the Problem

The FAST EZ-EFI system is a self-learning fuel injection system that requires proper installation and attention to details for optimal performance. One common issue observed by users is a rich-running engine, which can be caused by various factors, including exhaust leaks.

When an exhaust leak is present, it creates an exhaust pressure spike that travels down the exhaust pipe and exits after the muffler. This pressure spike generates a low-pressure pulse that travels back up the pipe towards the engine. This low-pressure spike acts like a siphon, pulling fresh air into the exhaust system through the leak.

Impact on Self-Learning EFI Systems

All self-adapting EFI systems use a wide-band oxygen sensor placed downstream in the exhaust system to monitor the amount of free oxygen in the exhaust. The sensor's readings are used as feedback for the engine control unit (ECU) to adjust the air-fuel ratio. Exhaust leaks introduce additional oxygen into the system, fooling the oxygen sensor into thinking the engine is running lean. As a result, the ECU adds more fuel to the engine, leading to a rich-running condition.

Troubleshooting and Solutions

To resolve fuel pressure and exhaust leak issues:

• Carefully inspect the exhaust system: Pay close attention to the gasket between the header and the head, the collector flange, the WBOS mounting bung, and the joints where two exhaust pipes are welded together. These are common areas for leaks.
• Use smoke to check for leaks: Commercial smoke generators or homemade smoke leak detectors can help identify even minor cracks or leaks in the exhaust system.
• Address any identified leaks: Eliminating leaks will significantly improve the performance of your fuel injection system.
• Consider an alternative EFI system: Some users have reported switching to alternative EFI systems, such as Holley Sniper XFLOW, after experiencing issues with the FAST EZ-EFI.
• Check fuel system components: Ensure your fuel pressure regulator, fuel injectors, and fuel pump are functioning properly and not contributing to the issue.
• Review installation and settings: Ensure the main power and ground wires are connected directly to the battery, as proper grounding is essential for EFI systems. Also, consider running through the initial calibration process again to reset the computer's memory.

Fuel pressure and ignition

However, there have been reports of issues with the FAST EZ-EFI system not holding fuel pressure after shut off, which can lead to hard starting and poor fuel mileage. This could be due to a faulty check valve, leaky injectors, or a bad fuel pressure regulator. It is important to troubleshoot and diagnose these issues properly to ensure the engine is running optimally.

To maintain fuel pressure after shut off, it is crucial to have a properly functioning fuel pressure regulator. The regulator controls the fuel pressure in the system and ensures that it stays within the desired range. Leaky injectors can also cause fuel pressure to drop, as the fuel leaks out of the injectors and back into the system. Additionally, a faulty check valve can allow fuel to flow back into the system, resulting in a loss of fuel pressure.

It is also important to consider the design of the fuel pressure regulator. Some adjustable fuel pressure regulators are not designed to hold pressure on the flow and returns, which can lead to a drop in fuel pressure after shut off. This can be mitigated by using a check valve, but it may not completely solve the issue.

In conclusion, fuel pressure and ignition are critical aspects of engine performance, and the FAST EZ-EFI system is designed to maintain fuel pressure after shut off. However, issues with the system not holding fuel pressure can occur, and it is important to troubleshoot and diagnose these problems properly. A properly functioning fuel pressure regulator, leak-free injectors, and a functional check valve are key to maintaining fuel pressure and ensuring optimal engine performance.

Fuel pressure and fuel pump relay

The fuel pump relay is an essential component of a vehicle's fuel system, and problems with it can lead to issues with fuel pressure and engine performance.

The fuel pump relay is an electronic component that supplies a consistent voltage to the fuel pump when the ignition is turned on. This voltage activates the fuel pump, which creates pressure in the fuel lines to push gasoline to the combustion engine. Thus, the fuel pump relay plays a vital role in ensuring the engine receives the fuel it needs to function.

When the ignition is shut off, the fuel pump relay powers down the fuel pump. This process is crucial for maintaining the proper fuel pressure in the system. If the fuel pump relay malfunctions, it can lead to issues such as the engine refusing to start or suddenly stalling.

In most vehicles, the fuel pump relay is located in the fuse box in the engine bay, often in a long black box along with other fuses and relays. However, it can also be found in other locations, such as under the hood, on the firewall, or near the steering column.

To test a fuel pump relay, it can be temporarily swapped with another relay of the same design from the power distribution box. If the fuel pump runs with the alternate relay installed, it confirms that the original fuel pump relay needs to be replaced.

Maintaining proper fuel pressure is essential for optimal engine performance. Issues with the fuel pump relay can lead to fluctuations in fuel pressure, impacting the engine's ability to receive the necessary fuel for combustion. Therefore, it is crucial to ensure the fuel pump relay is functioning correctly and that the fuel system holds the appropriate fuel pressure, even after the engine is shut off.

Fuel pressure and fuel injectors

Fuel injectors are devices that deliver fuel to the engine. They are controlled by the engine control unit, which ensures that the correct amount of fuel is injected into the cylinders. The ECU calculates the amount of fuel required based on various sensor readings, such as engine speed, load, temperature, and airflow.

Fuel injectors are essential components of modern fuel injection systems, which have largely replaced carburetors as the primary means of fuel delivery in automobiles. Fuel injection systems offer several advantages over carburetors, including improved fuel efficiency, reduced emissions, and better performance.

Fuel injectors work by spraying a precise amount of fuel into the engine's intake manifold or directly into the combustion chamber. This fuel is then mixed with air before being drawn into the cylinders, where it is ignited by the spark plugs to produce power.

To function properly, fuel injectors require a certain fuel pressure, which is typically provided by a fuel pump. This pressure ensures that the fuel is atomized into a fine mist, which promotes more complete combustion and improves engine performance.

It is important for the fuel injectors to maintain fuel pressure even after the engine has been shut off. This is because the fuel pressure helps to prevent vapor lock, which can occur when the fuel vaporizes due to heat and creates air bubbles in the fuel lines. Vapor lock can lead to starting problems and engine stalling.

Additionally, maintaining fuel pressure after engine shutdown helps to ensure that the fuel injectors are ready to deliver fuel when the engine is started again. This can improve cold-start performance and reduce the amount of time required for the engine to reach its optimal operating temperature.

In some cases, issues with the fuel system may cause a loss of fuel pressure after the engine is shut off. This can be due to leaky injectors, a faulty fuel pressure regulator, or a malfunctioning check valve in the fuel pump. Diagnosing and addressing these issues is important to ensure the proper functioning of the fuel injection system.

Fuel pressure and fuel return line

The FAST EZ-EFI fuel injection system is reported to have issues with holding fuel pressure. Some users have reported that the system does not hold fuel pressure after shut off, leading to hard starts and decreased fuel efficiency. There are several potential causes for this issue, including a faulty fuel pressure regulator, leaky injectors, or a faulty check valve in the fuel pump.

To diagnose the issue, it is recommended to check for fuel leaks, test the fuel injectors, and ensure that the fuel pressure regulator and check valve are functioning properly. In some cases, it may be necessary to replace these components to resolve the issue.

It is also important to note that the FAST EZ-EFI system has been reported to have other issues, such as running rich, stalling, and difficulty with tuning. Some users have expressed dissatisfaction with the system and have opted to remove it and switch back to a carburetor or a different fuel injection system.

Frequently asked questions