Replacing Fass Fuel Filters: Step-By-Step Guide

Changing the filters on a FASS fuel system is a relatively straightforward process, but there are a few things to keep in mind to ensure it is done correctly. It is important to know the type of vehicle you are working on, as the process may vary slightly for different models. In general, you will need to replace the fuel filters and the water separator, and possibly prime the system. There are a few different methods for priming the system, including manually pumping, running the pump and cracking the filter, or using a screwdriver to push the Schrader valve while pumping. It is also recommended to use fresh fuel when filling the new canisters to avoid any contamination.

Unscrew old filters and put new ones on

To replace the filters on your FASS fuel system, you will need to first locate the filters. Typically, there are two filters on the pump and one on the engine. Once you have located the filters, you can proceed to unscrew them. Place a bucket underneath the filters to catch any fuel that may leak out. Turn the filters counterclockwise to unscrew them. Once the old filters are removed, you can install the new ones. Screw the new filters into place by turning them clockwise. Make sure they are tight and secure.

When replacing the filters, it is recommended to use fresh fuel to fill the new canisters before screwing them in. This is because you may not know the history of the vehicle, including the quality of fuel used and how long the filters have been in place. By using fresh fuel, you can ensure that the new filters are not contaminated. However, if you do not have fresh diesel, you can gently pour the fuel from the old filters into the new ones.

It is important to note that you should also replace the water separator in addition to the fuel filters. The water separator should be filled with fuel to decrease the chances of air in the system, which can cause hard starting conditions. This is a preventative measure to ensure the optimal performance of your vehicle.

Prime using the fuel filter head

To prime your FASS fuel system, you will need to fill both filters and screw them on. Then, run the pump and open the front filter on the FASS (not the water separator) to allow fuel to leak/spray out. Tighten the filter when a steady flow and sound come from the pump. This process will bleed all the air out of the FASS and ensure it runs as quietly as possible.

To avoid getting diesel everywhere, you can wrap the service port with a rag or two, push the Schrader valve with a screwdriver while pumping. This method will also prevent starting hesitation.

If you are priming the FASS pump for the first time, you can fill the filters with diesel before screwing them on and starting the engine. However, this is not necessary, as the FASS pump is self-priming and will fill the filters itself.

Make sure you have at least 5 gallons of fuel in the tank, or you will see small air bubbles constantly.

Turn the key on to start the pump

To turn the key on to start the pump, you must first ensure you have at least five gallons of fuel in the tank. This is important because, without sufficient fuel, you will encounter small air bubbles, which can be problematic. Once you have confirmed adequate fuel levels, you can proceed by turning the key. This action will activate the FASS pump, initiating the fuel flow.

It is worth noting that this step is part of the priming process for the FASS pump. Priming is essential to ensure the pump functions quietly and efficiently, and it involves filling both filters, screwing them on, and running the pump. The front filter on the FASS, which is not the water separator, should then be cracked open so that fuel leaks or sprays out. This step may be messy, so it is advisable to have a bucket or some sort of container ready. Once you observe a steady flow of fuel and hear a consistent sound from the pump, you can tighten the filter.

An alternative method for priming the pump is to wrap the service port with a rag or two and push the Schrader valve with a screwdriver while pumping. This technique can be quicker and less messy than the previous method.

By following these steps and turning the key to start the pump, you will be well on your way to successfully changing the filters on your FASS fuel system.

Fill filters, screw on and run the pump

To prime the FASS pump, you need to fill both filters, screw them on, and run the pump. Here is a step-by-step guide:

First, fill both filters. This is important to ensure that the system has enough fuel to function properly. Make sure you have at least 5 gallons of fuel in the tank, as a lower fuel level can cause air bubbles in the system.

Next, screw on the filled filters. Ensure that they are tightly and securely fastened to prevent any leaks.

Now, run the pump. As the pump operates, you will need to crack open the front filter on the FASS (not the water separator) to bleed the air out of the system. This step can be messy, so it is recommended to have a bucket nearby to catch any leaking fuel. Keep the filter cracked open until you hear a steady flow and sound from the pump, indicating that the air has been removed from the system.

Finally, tighten the front filter when you achieve a steady flow and sound. This will ensure that the system is sealed and running quietly.

By following these steps, you will successfully fill the filters, screw them on, and run the pump to prime your FASS fuel system.

Crack the front filter to bleed air out

To crack the front filter to bleed air out of a FASS fuel system, you must first fill both filters, screw them on, and run the pump. Then, you can crack the front filter on the FASS (not the water separator) so that fuel leaks or sprays out. It is important to note that this process can be quite messy, and you will need a bucket to catch the leaking fuel. Once you observe a steady flow and sound coming from the pump, tighten the filter.

This process is necessary to bleed all the air out of the FASS system and ensure it runs as quietly as possible. By following these steps, you can effectively remove air from the fuel system and improve fuel delivery.

Additionally, it is recommended to have at least five gallons of fuel in the tank to avoid seeing small air bubbles constantly, which can be an indication that air remains in the system.

Frequently asked questions