Setting Fass Fuel Pump Pressure: Optimal Performance Tips

FASS fuel pumps are typically set to a pressure of between 14 and 18 psi, although some users have reported pressures of 9-10 psi. The pressure can be adjusted by contacting FASS and requesting a spring with the desired psi, or by stretching the return spring. However, stretching the spring may not be a long-lasting solution as it will eventually return to its original shape. It is also possible to adjust the pressure by adding a washer to shim the spring, which can raise the pressure.

FASS fuel pump pressure regulator

The FASS Adjustable Fuel Pressure Regulator (FPR) allows you to fine-tune your fuel pressure to meet the exacting requirements of modern diesel trucks. With many drivers running highly modified injection pumps and high-output injectors, a standard pre-set lift pump is insufficient. The FASS FPR enables drivers to set the pressure from their lift pump to their desired level between 0-100 PSI.

FASS has also engineered a boost compensation port in the FPR. This allows you to run an airline from your intake manifold, so that as additional air pressure (boost) is detected, the regulator will deliver incrementally increased fuel pressure. This is particularly beneficial during active acceleration when fuel demand is higher.

The FPR is manufactured from 6061 T-6 aircraft-quality aluminium to meet the high standards FASS has set for the diesel industry. The quality of the FPR is backed by an available four-year warranty.

The FASS FPR is designed for those with pumps that do not have an external/adjustable regulator. These pumps typically use a spring and ball to regulate fuel pressure, with the spring provided by the pump manufacturer. The spring should provide adequate pressure, typically between 16-18 psi. However, the springs can be inconsistent, leading to erratic fuel pressure readings.

If you are experiencing erratic fuel pressure, you can try straightening and reinstalling the spring or replacing it entirely. You may also want to consider using a Viton ball, which is made from a stronger material than the Buna ball that comes with FASS pumps.

Increasing FASS fuel pressure

The FASS Adjustable Fuel Pressure Regulator (FPR) allows you to fine-tune your fuel pressure to meet the exacting requirements of modern diesel trucks. With many drivers running modified injection pumps and high-output injectors, a standard pre-set lift pump does not deliver adequate pressure. The FPR from FASS allows the driver to set the pressure out of their lift pump to their requirements, from 0-100 PSI.

Boost Compensation Port

As an added benefit, FASS has also engineered a boost compensation port. This will allow you to run an airline from your intake manifold so that as additional air pressure (boost) is seen, the regulator will deliver incrementally increased fuel pressure. This is very beneficial when under active acceleration and fuel demand has increased.

Adjusting the PSI on a FASS Fuel Pump

The FASS fuel pump pressure can be adjusted by modifying the return spring. The spring is located behind the return fitting that sends excess fuel to the fill neck. To increase the pressure, you can either stretch the existing spring or replace it with a new one with higher PSI.

Stretching the spring involves removing the return line, taking out the spring, stretching it, and then reinstalling it. This method is not as precise as shimming and may not be permanent, as the spring may eventually return to its original shape.

Alternatively, you can contact FASS or a FASS dealer to purchase a new spring with the desired PSI rating. It is recommended to consult with FASS or a dealer to ensure you get the correct spring for your specific pump.

In addition to adjusting the spring, you can also try bleeding the system to eliminate the possibility of a vapor lock problem. This involves loosening the bleed valve on the water separator filter while the engine is running, which will allow air to escape.

It is important to note that increasing the fuel pressure may not result in any noticeable performance differences. Additionally, some FASS pumps are designed for high volume and low pressure, so increasing the pressure too much can put the pump in the red as far as amperage goes. Always be cautious when making adjustments to your fuel system and consult with experts or mechanics if you are unsure.

FASS 150 fuel pump pressure

The pressure of a FASS 150 fuel pump depends on several factors, including the vehicle's make and model, engine specifications, and the pump's design and adjustments. Here is some detailed information about the FASS 150 fuel pump pressure:

• Vehicle-Specific Pressure Range: The optimal fuel pump pressure can vary depending on the specific vehicle and engine setup. For example, one user with a 1998.5-2002 2nd Gen Dodge 5.9L 24V Cummins engine reported that their FASS 150 fuel pump pressure remained relatively constant, typically between 14 and 15 PSI, regardless of load or engine speed. Another user with a similar vehicle suggested that the pressure should not drop below 10 PSI at idle and should ideally stay above 4 PSI under wide-open throttle (WOT) conditions. These values can serve as a reference point for vehicles with similar specifications.
• Factory Settings and Adjustments: FASS fuel pumps are typically pre-set at the factory to deliver a specific fuel pressure range. The standard pressure range for FASS 150 fuel pumps is often between 7-9 PSI to 11-13 PSI. However, it's important to note that FASS offers adjustable fuel pressure regulators, allowing users to fine-tune the fuel pressure according to their vehicle's requirements. These regulators provide full adjustability from 0-100 PSI, accommodating a wide range of applications, including highly modified injection pumps and high-output injectors.
• Spring and Ball Mechanism: The FASS 150 fuel pump typically uses a spring and ball mechanism to regulate fuel pressure. The spring is located in the main pump body, and by swapping out this spring, you can increase the output pressure. This modification can raise the pressure from the standard 7-9 PSI to a higher range of 11-13 PSI. Additionally, the choice of ball material can impact fuel pressure readings. Some FASS pumps use a Buna ball, while others may use a Viton ball, which is made of stronger material and can help maintain consistent fuel pressure.
• Addressing Erratic Fuel Pressures: In some cases, users may experience erratic fuel pressure readings or lower-than-expected pressures. This can be attributed to inconsistencies in the spring or issues with the ball mechanism. Straightening or replacing the spring, as well as ensuring the correct ball material is used, can help resolve these issues. Additionally, adding a washer/shim between the fitting and the spring (not between the spring and ball) can help raise the fuel pressure if needed.

It is important to consult a professional or a FASS representative for specific instructions and recommendations regarding your particular vehicle and fuel pump setup.

Installing a pump pressure gauge

Step 1: Purchase the Correct Gauge

Before you begin the installation process, it is important to purchase a suitable fuel pressure gauge for your FASS fuel pump. Ensure that the gauge is designed for diesel fuel systems and that it has the appropriate pressure range (0-100 PSI) and accuracy for your needs. You can find these gauges at most auto parts stores or online.

Step 2: Determine the Location of the Gauge

Decide where you want to mount the gauge. You can choose to mount it inside the cab or outside, depending on your preference and the layout of your vehicle. If you opt for an outside mount, consider a location that is easily accessible and visible, such as on the fuel filter housing or the overhead console.

Step 3: Gather the Necessary Tools and Materials

Make sure you have all the tools and materials needed for the installation process. This may include wrenches, screwdrivers, adapters, T-fittings, needle valves, and tubing. The specific tools and materials will depend on your vehicle's setup and the location of your fuel pump.

Step 4: Access the Fuel Pump

Locate your FASS fuel pump and gain access to it. This may involve removing certain components or panels to create enough workspace. Be careful not to damage any surrounding parts or connections during this process.

Step 5: Identify the Port for the Gauge

The FASS fuel pump typically has an existing port where you can install the fuel pressure gauge. This port is usually located in the fuel hat or where the line connects to the VP44. Refer to your FASS fuel pump's manual or consult a mechanic if you are unsure about the exact location.

Step 6: Install the Fuel Pressure Gauge

Follow the instructions provided with your fuel pressure gauge to properly install it into the identified port. Ensure that all connections are secure and tight to prevent leaks. If you are using an electronic sensor, pay attention to the wiring and ensure it is long enough to reach the desired location of the gauge.

Step 7: Test the Gauge

Once the installation is complete, start your vehicle and allow it to reach operating temperature. Monitor the fuel pressure gauge to ensure that it is providing accurate and stable readings. Compare the readings with the recommended pressure range for your FASS fuel pump.

Step 8: Make Adjustments as Needed

If the fuel pressure readings are not within the desired range, you may need to make adjustments to your FASS fuel pump or the gauge itself. Consult a professional or refer to the manufacturer's instructions for guidance on adjusting the fuel pressure.

Step 9: Secure and Route the Wiring (if applicable)

If you are using an electronic fuel pressure gauge, ensure that the wiring is securely fastened and routed away from any moving parts or high-temperature areas. This will help prevent damage to the wiring and ensure the gauge's functionality.

Step 10: Finalize the Installation

Once you are satisfied with the fuel pressure readings and have secured all connections, finalize the installation by reinstalling any removed components and cleaning up the work area. Test your vehicle to ensure that it is operating smoothly with the newly installed fuel pressure gauge.

By following these steps, you can successfully install a pump pressure gauge for your FASS fuel pump, providing you with valuable insights into your fuel system's performance and helping you maintain optimal fuel pressure.

Adjusting FASS fuel pump pressure

FASS fuel pumps typically do not come with a way to easily adjust fuel pressure. The pump manufacturer usually provides springs to regulate fuel pressure, which is typically between 14 and 18 psi. The springs can be inconsistent, causing erratic fuel pressure or lower-than-expected readings.

If you are experiencing erratic fuel pressure, you can try straightening or replacing the spring. FASS support can provide a replacement spring. Alternatively, you can try using a Viton ball, which is made of stronger material and may help to stabilise the pressure.

If you are still experiencing low-pressure issues, you can try adding a washer to shim the spring and raise the pressure. The washer should be placed between the fitting and the spring, not between the spring and the ball.

You can also increase the FASS fuel pump pressure by ordering a new spring with the desired psi from FASS. However, note that increasing the psi too much may cause issues with the pump's functionality. For example, a FASS 150 pump may not be able to handle pressures above 40 psi without a new motor and T-block. Additionally, higher psi can cause the truck to start loping, and too much pressure can reduce the flow rate of the pump.

For a FASS 150/150 pump, you can try stretching the return spring to increase the pressure. To do this, remove the return line, take out the spring, stretch it, and then reinstall it. However, be aware that the spring may eventually return to its original shape, causing the pressure to drop back down. Another option is to shim the spring with a washer, which is a more precise method that can be easily reversed if you don't like the results.

Frequently asked questions