FASS Vs. AirDog Fuel-Air Separation System

Which one is the best – FASS vs. AirDog? For any automobile vehicle, good engine performance is a must. However, it is best achieved when your fuel is pure. The best way to work this is to get a fuel separation system. 

There are two predominant fine-quality fuel separations – FASS Vs. AirDog, which is often debated. 

The fuel separation segregates between the contaminants mixed in the water/vapor. These are difficult to filter normally and can get tricky. However, whichever fuel pump works the best to improve, it would surely develop its engine performance.

So, how do you choose between – FASS vs. AirDog? To answer all your questions, we have a pros and cons list to weigh the two top products. So, tag on till the end as we compare between the Fass Vs. Airdog fuel air separation systems in detail.

Fuel-Air Separation Systems

When it comes to maintaining your diesel efficiency, there can be no compromise. You have to select the best of the best. Besides, you need to maintain good filtered engine efficiency. So, you need the purest diesel available.

Hence, you need to use the best air purification system to filter all the minute unwanted impurities in your diesel. These pass-through fuel filters give you a diesel fuel lift pump.

So, these improve your engine’s performance, and they increase the fuel’s level to the fuel tanks to the fuel system. Therefore, this way, you can get rid of the contaminants. 

Like many comparisons occurring between the product brands like Marvel Mystery Oil vs. Seafoam, fuel additives are always on the debate for the best.

For this, the two-top fuel-air separation systems commonly used are FASS and AirDog. Both give good performance to the engine. Still, which works best? 

Hence, First, let’s look into the mechanism of how each works one by one.

FASS Fuel System

The FASS system is a consistent quality diesel producer whose name translates to the Fuel Air Separation System. This company’s products produced in the United States have been selling to all class 8 owners worldwide for the past 19 years. 

The fuel system comprises filtration separators and a fuel lift pump that runs on diesel. 

So, this way, it cleans up the impurities of water and vapor-like dirt and moisture. By doing this, it makes sure the horsepower, torque, and throttle response work well. 

Thereby, it increases the total engine performance and fuel mileage with good oils. Moreover, the smooth sailing of the fuel reduces any noise from the engine. 

While most systems use a combined two complementing systems, FASS uses only one patented method to remove the contaminants. 

Also, air bubbles stop fluid damping, which increases the tip impact by 50% and can lead to impairment in the injected tip. So, the FASS system get rid of these impurities before the fuel contacts the engine.


AirDog Fuel System

The Pureflow AirDog is considered an original fuel-air separation system famous for tailor-made manufacturing, which gives excellent performance. The manufactures from these industries have skilled expertise of experience in this brand for more than 25 years.

An AirDog fuel system serves as a conduit between a fuel tank and the engine. So, here the fuel is purified before being sent to the tank. Here, the fuel goes through a water separator filter media that separates it from contaminants. 

When the fuel tank is full of pollutants such as dirt, air bubbles, and moisture, the AirDog system receives the fuel under a vacuum from the tank. These substances obstruct the flow of fuel and, as a result of wear and overheating, impair the engine’s performance.

The fuel filter has two passageways. A passageway for the fuel to pass through the engine through the fuel pickup tube.

Furthermore, the excess fuel goes out through the pressure regulator back to the fuel tank, and the process is repeated. Here, the fuel pressure gets controlled by the regulator. They combine the vapor or air with foam while it returns to the fuel tank.

FASS Vs. AirDog – Major Similarities 

Other than the fact that these two products started from the same manufacturing companies called the apex, the FASS and AirDog have other similarities. That is what makes it difficult to select the better one. 

  • Both reduce noise efficiently.
  • Rise the lubricity and gives a smooth flow, thus stopping any damage to the engine components
  • Both the fuel pumps, after installation, leave about 1 to 2 inches of fuel line to remain in the pump.
  • The two brands use lock adaptors for the fuel lines for better seating  
  • Prevent air bubbles from popping near the tip, which stops breakage or engine heat-ups
  • The wiring in both models is the same.
  • In terms of purification, both work well as they filter out the contaminants like air, water, vapor, and dirt from the fuel.

FASS Vs. AirDog – Major Differences

The key differences between the two popular brands, FASS and AirDog, are what separates them while choosing the best. So, let’s look at the major differences that set Fass and Airdog apart from each other. 

  • The fuel lines are different – FASS has a 3/8-inch fuel line, whereas AirDog has a 1/2-inch fuel line. 
  • The AirDog’s steel connectors and AN Fittings make it a better connector and fitter than FASS to the fuel lines.
  • FASS needs only one method to remove contaminants, whereas AirDog uses a combination of two complementing systems.
  • While the AirDog has a 2-micron filter set, the FASS comes with 3-micron filters making AirDog’s filter superior.
  • The pickup tube materials in both of the products are different. The FASS is made with a steel pickup tube, whereas AirDog is made with plastic.
  • Even though the brackets are steel powder coated in both models, the FASS is more specific, while the AirDog is more generic. However, the FASS provides quicker installation facilities, and the AirDog provides better flexibility. 
  • The wiring in the FASS fuel pump does not need the power wire for the OEM pump.
  • The size of the FASS filters is 1.5 times larger in size than the AirDog ones. So, if you need a smaller unit, you can use AirDog, whereas FASS can withstand for a long time.
  • Although both are good when it comes to the noise function, AirDog is comparatively better as they do not produce any sound. It can be because the FASS produces some lawn mowing noise from the outside, whereas inside, it is quiet.

FASS vs. AirDog: A Detailed Comparative Guide

For selecting the best for your engine, you might want a clear comparison between the two. So, a detailed contrast of the two products in terms of performance, reviews, features, pros, and cons of each might be likely what you need. 

Moreover, this way, you get to see the efficiency and effectiveness of the components between the two brands’ products – FASS vs. AirDog. So, let’s look at them in detail to select the best.

Engine Performance 

A better engine performance gives you a smooth sailing of your vehicle. Engine performance can get affected by many factors like oil mileages, leaks, fans, diesel, and more. Hence, it would help if you were always careful to choose the best quality product available. 

For instance, selecting the best leak sealants would easily stop large leaks and improve performance. Here, analyzing the FASS vs. AirDog engine performance would let you know which one can last long and perform well.

FASS Performance

The FASS titanium system has a mass flow return rate of 95 gph. These can include all kinds of impurities. Moreover, the radiance cuts the FASS system can cut the smooth diesel flow in the injectors easily. 

Therefore, the titanium signature series of the FASS pump can flow for 290 gallons per hour with 20 psi. 

Also, they can undergo radius cuts and come with a high tolerance level to other gears. So, this clears out the stagnant fuel from accumulating in 90-degree corners.

AirDog Performance 

The Pureflow AirDog system operates by analyzing the maximum level in engine requirement. Here, the fuel passes through the contaminated impurities and moisture. 

It reaches the water separator, where the particles can get clogged in the greater pump and separated from the water.

Afterward, this semi-clean fuel moves in the fuel pump, where it gets rid of the tiny particles like a vapor, water, and air by passing through the filter membrane. Then, this gets eliminated by the primary air discharge port from the tank to the regulator. 

Hence, the first passage contains the clean fuel and the second the disposed of fuel. 

The outflow of the AirDog system goes to the impressive 200 gph outflow giving an efficient performance.

Lubrication Effects 

Smooth lubrication of the diesel to flow effectively without getting clogged or stuck is crucial while fueling an air separation system. 

Better lubrication can even get rid of air bubbles or other clogs and are purely made. Thus, this results in efficient lubrication for the fuel engine to continue running properly.

FASS Titanium Series

The advanced machining technique it uses can make smooth flowing cuts in the aluminum housing. Also, they help with raising the fuel flow in the pumps.

Furthermore, these obstruct the ‘galling effect’ as they ensure smooth lubrication. Since, if this effect occurs, FASS makes it difficult for the diesel to move. It is common when metal surfaces come in contact with each other. 

Purified AirDog series

The AirDog pump, much like the FASS system, reduces galling and improves lubrication. Then, this gives you a better throttle response which makes for a smoother ride.

Also, this separation system is efficient in removing the bubbles, which improves engine performance and lubrication. 

FASS Vs. AirDog: Their Key Features

A comparison of the key features of the FASS and AirDog fuel air separation system

FASS – Fuel Air Separation System

  • Complete contaminant removal for all types of impurities
  • Increase Horsepower and Torque
  • Fass Wisper Technology
  • Performs radius cuts
  • Extreme Water separator filter
  • Better fuel mileage
  • American Motor
  • 95 gph outflow
  • Mass flow return
  • The lift-type is electric

AirDog – Fuel Air Separation System

  • Vehicle specific fit type
  • Certified for frustration-free
  • Dodge Cummins
  • Dual feed gerotor
  • Quick components connection
  • Adjustable pressure regulator
  • Good shaft
  • 2 Microns fuel filters
  • Mounts to frame
  • 200 gph outflow

FASS Vs. AirDog: Pros and Cons 

While selecting the best fuel separation pump, it is necessary to weigh out the benefits and limitations. These you might face due to choosing the product.

FASS – Fuel Air Separation System


  • Good at shock absorption
  • Can Kickstart easily 
  • Engine performance is consistent
  • Less engine maintenance cost
  • Protects against injector systems
  • Separates Fuel Contaminants 
  • Less heating up of the fuel
  • Stops cutting torch effect
  • Unique Radius cutting feature
  • Reduces carbon monoxide and carbon dioxide
  • Increased fuel mileage (30,000 mph)
  • Increases lubrication 
  • 4-year warranty


  • Installations are difficult- the User -manual does not have clear instructions.

Airdog – Fuel Air Separation System

  • Can Kickstart easily with self-priming
  • Engine performance at optimal levels
  • No engine noises
  • Protects against injector systems
  • Separates Fuel Contaminants and favor fuel.
  • Less heating up of the fuel
  • Increases torque and Throttle response
  • Stops cutting torch effect
  • Maintains fuel economy
  • Reduces all exhaust emissions
  • Increased fuel mileage (30,000 mph)
  • Increases lubrication 
  • Affordable
  • Demand flow return
  • Installation is easy with proper user-manual


  • Shock absorption takes time
  • Warranty is not proper

FASS Vs. AirDog- Which’s better?

When comparing both the products for it is difficult to come up with a clear winner. Since both have good performance and work efficiently, where one product lacks other products equally balances it out.

However, to select the best, you need to consider your budget and look at the prices. The airflow system comes at a lower price than the FASS system. Also, the noise whispering system is well-advanced in the AirDog system.

The double separation system also effectively reduces bubbles to produce better fuel economy and performance in AirDog. So, it can be considered better and simple to install. Moreover, its manual contains clean instructions.

However, the FASS radius cutting feature is unique in that it prevents it from forming 90-degree bends and stagnating in any area. 

Both the products work well against the contaminants. The FASS stays long and has better mileage, and can last long. These can run up to 800K miles. Also, they increase horsepower and torque.

However, AirDog comes in a compact style and is light weighted. It also contains two passageways. 


FASS vs. AirDog Systems: FAQ’s

What is a lift pump? What does it do?

A lift pump is a fuel supplying pump from the tank which transfers it to the vehicle through the injection system. This low-pressure supply fuel goes from the pump to the engine.

Also, the lift pumps come in aftermarket or OEM supply, where these allow a minimum of 8 psi pressure supply. In the old model, these systems come through the mechanical injection system, whereas the new model of the pump comes attached to the engine.

Also, the power of your diesel engine increases when you use aftermarket lift pumps. Here, the fuel gets directly supplied to the engine, which increases the performance.

It is important to purchase diesel lift pumps rather than gasoline pumps where the diesel fuel won’t work. A pump and filter combination increased the high performance of the lift pump, which increased the filtration capacity. 

What looks different between the original AirDog and AirDog II-4G pumps?

The new AirDog II-4G has the new upgraded version of AirDog. Hence, this separates contaminated particles by using the latest technology. So, this version has a different pump and base assembly design.

Moreover, these came in low amperage motor power, and the dual inlet design flows to the gerotor. So, with this, it can easily get their fuel volume to be high easily. The regulator that comes in the AirDog II-4G is adjustable and to handle.

Which lift pump is best for the trucks?

AirDog lift pumps work best for trucks due to their compact size easily transported to pump for a truck. Usually, 500 horsepower supplies 100 units. AirDog products, the AirDog 150 and AirDog 165 are ideal for helping carry a huge horsepower of 1,000 units. 

Using a suction tube or kit is recommended in the tank fuel pumping.

Final Thoughts 

When confused between two products, comparing their advantages and disadvantages are the possible solution. However, you should see which feature you would find comfortable and resonating when you contrast the two.

Likewise, the two best fuel air separation systems, FASS and AirDog pump lifts have had their fair share of pros and cons equally balanced. 

Nevertheless, some might find the FASS system to work well, while others might be comfortable with the AirDog. However, it would help if you chose a careful analysis of both the lift pumps. Now, try these lift pumps and improve your engine efficiency.

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