Fuel Pressure Requirements For Nos Sniper Kit Explained

The NOS Sniper EFI kit is a popular choice for those seeking an easy bolt-on power upgrade. It is a wet nitrous oxide kit designed for 4, 6 and 8 cylinder engines, providing up to 125 hp. The kit includes all necessary components for installation, such as the exclusive NOS soft-plume fogger nozzle, steel bottle brackets, an orange sniper 10lb bottle, and detailed instructions. It is important to note that while a stock fuel pump should be sufficient, one must ensure it meets new specifications as older pumps may decline in performance. Additionally, premium-grade pump petrol or unleaded racing fuel is recommended. The Sniper EFI also allows for manual correction of fuel pressure in the software, with a desired fuel pressure of 59-60 PSI.

The ideal fuel pressure for the Holley Sniper Kit

Checking Fuel Pressure

To check the fuel pressure, you can hook up a mechanical gauge and observe the reading while the engine is running. This can be done by connecting the gauge to an unused port and running a hose to the dashboard area.

Fuel Pressure Regulator

The Holley Sniper Kit has a built-in fuel pressure regulator, which maintains a steady fuel pressure of 58.5 to 59.5 psi under all conditions. The regulator is typically a small device in the engine bay with a minimum of three connections: one from the fuel supply line, one output to the Sniper, and one output returning to the tank.

Fuel System Requirements

In addition to the fuel pressure regulator, there are several other fuel system requirements to note when using the Holley Sniper Kit. These include:

• Fuel Pump: A high-pressure electric fuel pump is required to deliver the necessary fuel pressure. Options include an electric in-line pump, an electric in-tank pump, or a replacement fuel tank with an integrated pump.
• Fuel Line: A 3/8" fuel injection-approved hose is recommended for the supply and return plumbing.
• Fuel Filters: A 100-micron pre-filter and a 10-micron post-filter are required for the Holley Sniper Kit.
• Fuel Fittings: All Sniper EFI systems use -6AN fuel inlet/outlet connections, with higher horsepower applications requiring the installation of an -8AN O-Ring fitting.

How to check fuel pressure

Checking your fuel pressure is a good first step when experiencing drivability issues with your vehicle and you suspect the fuel system. Here is a step-by-step guide on how to check your fuel pressure:

Step 1: Identify the Pressure Line

Most vehicles today have two fuel lines going to the engine: a pressure line and a return line. You will be checking the pressure on the pressure line. Refer to your vehicle manufacturer's instructions to safely attach a pressure gauge.

Step 2: Bleed the Pressure from the System

Before attaching the pressure gauge, you will need to bleed the pressure from the system. This can be done by removing the fuel pump relay, which will cause the vehicle to attempt to start with low pressure.

Step 3: Attach the Pressure Gauge

Once the pressure has been released, open up the system and install a pressure gauge. Be sure to have a rag handy to catch any fuel that may drip out of the line.

Step 4: Start the Vehicle and Check Pressure

With the vehicle running, time the release for about 15 seconds. After 15 seconds, release the valve and then measure the fuel pressure. If the pressure drops off very quickly, you may be experiencing a hard start issue.

Step 5: Monitor Residual Pressure

After releasing the valve, monitor the residual pressure for about 15 minutes. If, after 15 minutes, you are still holding good residual pressure, then your check valve and pressure regulator are functioning properly.

Step 6: Release Pressure and Remove Gauge

Before removing the pressure gauge, release the pressure from the system by starting the vehicle and allowing the pressure to bleed off. Have a rag handy to catch any fuel that may drip out.

Additional Tips:

• If you are experiencing issues with your vehicle not starting, it is important to first check that there is gas in the tank, as fuel gauges can sometimes be faulty.
• If there is gas in the tank, the next step is to verify that the fuel pump is working. Do this by listening for a two-second whir, hum, or series of rapid clicks as the fuel pump pressurizes the fuel line to the engine.
• If there is no noise, check the fuel pump fuse and relay. If both are good, check the wiring to the pump.
• If voltage is present when turned on, then the pump has failed and should be replaced.

Checking Sniper EFI Fuel Pressure

If you are using a Sniper EFI system, Holley recommends testing the fuel pressure at the inlet of the sniper to confirm 60 psi. This can be done by hooking up a mechanical gauge and monitoring the pressure while the engine is running.

Troubleshooting Low Fuel Pressure

If you are experiencing low fuel pressure, there are a few potential causes:

• The fuel filter may be clogged.
• The pump could be failing.
• There may be improper tank venting due to a loose gas cap.
• The fuel pressure regulator may be faulty.

Fuel pressure regulators

The Sniper EFI kit is designed for Chevelles and Camaros, offering an easy conversion to electronic fuel injection. The success of such a system depends on a high-quality fuel delivery mechanism, and the kit includes a "pump-on-a-stick" system with a flange to mount the pump assembly inside a large reservoir at the front of the tank. This design ensures the pump is always submerged in fuel, improving efficiency and durability.

The standard Sniper system uses a 255-lph pump, delivering up to 550 hp worth of fuel at EFI pressures. However, an optional 400-lph pump is available for gasoline, increasing the capacity to 750 hp. This is ideal if you're considering an NOS nitrous system.

The fuel pressure regulator plays a critical role in this setup. Sniper EFI fuel regulators are designed for systems with a return line back to the tank and feature adjustable base pressure from 40-130 psi. They are constructed from billet aluminium and include a mounting bracket and hardware.

It is important to note that fuel pressure issues may be caused by factors other than the regulator, such as a blocked or undersized return line or a faulty gauge. Therefore, it is recommended to perform a series of tests to identify the root cause of any problems.

Fuel lines and fittings

The fuel lines provided by Holley are designed to be compatible with a wide range of fuels, including E85. It is important to use fuel lines that are compatible with the type of fuel you intend to use. Holley's UltraPro hose, for example, is made of carbon-infused PTFE, which is compatible with various fuels and offers excellent resistance to abrasion and corrosion. This type of hose also has the advantage of being lightweight and easy to route due to its convoluted wall construction.

When selecting fuel line fittings, it is important to ensure they are specifically designed for use with the chosen hose. In the case of the Earl's UltraPro PTFE hose, specific fittings are required to ensure a secure and leak-free connection. Fittings such as the Earl's 1/4 NPT to -6 male AN adapter are commonly used to connect the pressure outlet and return lines of the fuel pump. Additionally, it is recommended to use high-quality hose clamps, such as the 3/8-inch EFI hose clamps, to ensure a tight seal and enhance the overall appearance of the installation.

The fuel delivery system should be installed with careful consideration for routing and bend radius. The fuel lines should be routed away from potential sources of heat and abrasion. The stiffness of the fuel line material, such as carbon-infused PTFE, may require a wider bend radius to prevent kinking. It is also important to ensure that the fuel lines are securely mounted and supported to avoid vibrations or movement that could lead to leaks or damage.

In addition to the main fuel lines, the Holley Sniper EFI kit may require additional components, such as a fuel filter and regulator. A 10-micron fuel filter is commonly recommended for downstream filtering to ensure the removal of impurities. The filter can be installed anywhere between the tank and the EFI system fuel inlet, depending on the specific installation and requirements.

When assembling the fuel lines and fittings, it is crucial to follow the manufacturer's instructions and best practices. For example, when assembling the Earl's UltraPro hose, it is recommended to first pull back the outside cloth covering and then trim the inner tube flush with the end of the ferrule using a razor blade. This attention to detail during the assembly process ensures the integrity and safety of the fuel delivery system.

By selecting high-quality fuel lines and fittings, and following careful installation practices, you can ensure the reliable and efficient performance of your Holley Sniper EFI kit.

Fuel tank considerations

The Holley Sniper Kit offers an easy EFI fuel pump conversion for Chevelles and Camaros. The success of an electronic fuel injection conversion depends on a high-quality fuel delivery system. The Sniper fuel delivery system is designed to address this. The kit includes a Holley performance "pump-on-a-stick" system with a flange to mount the pump assembly inside a large reservoir at the front of the tank. This design ensures that the inlet to the pump is always submerged in fuel, improving efficiency and durability.

The Sniper kit also addresses the fuel tank itself, with a dedicated fuel tank that is one inch deeper than the stock tank to accommodate the in-tank pump. This tank has a capacity of 20 gallons and comes with new straps. The kit includes a pump and float level assembly, with the pump bracket requiring custom fitting to each tank. The depth of the pump should be measured accurately and set to place the inlet just off the floor of the tank.

The fuel hose material is an important consideration. The original system used older, rubber-lined braided steel hose, which can become brittle over time. A more durable option is carbon-infused PTFE, often referred to as "plastic fuel line". This material is extremely resistant to all types of fuel and offers a long lifespan. However, it is stiff and requires a wide bend radius to prevent kinks. Holley's UltraPro hose uses a convoluted wall construction that makes it lightweight and easy to route with a tight bend radius. It is also a safe conductor, preventing the build-up of static electricity.

Frequently asked questions