AirDog II-4G Diesel Lift Pump

by Air Dog


The Quietest, Longest Lasting, Best Performing Diesel Fuel System on the Market

The original AirDog was a game changer for the Diesel fuel market, filtering air, vapor, contaimients, and water out of diesel fuel. This increased longevity of engine parts and fuel economy, and of course power and torque! But that was only the beginning for AirDog. The second iteration brought about major improvements, especially in recirculating your excess fuel continually through the pump and allowing for adjustments in fuel pressure. The Air Dog II is a major improvement, decreasing aeration by adding in a low pressure return valve--something others in this industry just don’t seem to comprehend or be able to compete with. And as if that wasn’t enough, the brand new 4G motor is a true top of the line motor for a lift pump--I’d argue the best on the market. It is built to last, eliminates most vibration and noise and unnecessary wear and tear on the pump itself. And just think: there are customers out there who say they have original Air Dogs that have been running for nearly 2 million miles. The Air Dog II 4G edition could very well be the last fuel system you’ll ever need for your diesel pickup!

Bullet Point Breakdown of the AirDog II 4G

No time to read this whole article? Just want the quick and dirty dets? “Too long; didn’t read” your fav acronym? Don’t worry. We hear ya. Here’s our Midwest Aftermarket Bullet Point Breakdown of the Air Dog 2 4G:

  • AirDog Fuel Preporator for Diesel Engines: both AirDog I & 2 features include:
  • Increases fuel economy
  • Extends fuel filter life
  • Increases torque output
  • Makes your engine run quieter
  • Improves throttle response
  • Makes your engine have a smoother idle
  • Reduce exhaust emissions
  • Optimizes engine performance
  • Less Regeneration of DPF
  • It separates air from fuel: deaerates and deoxygenates fuel
  • Separates water and particulates out
  • Keeps proper pressure to the transfer pump
  • Eliminating cavitation and vapor from forming in your diesel fuel
  • Improves Diesel engine performance
  • CARB Certified
  • 4G Specific features go above and beyond those of the original Air Dog:
  • 4G motor: quietest on the market and best  performance
  • Perfectly centered gear rotor, eliminates shaft vibrations and noise
  • Upgraded ball bearings for longevity 
  • A innovative new lovejoy coupler eliminates even more vibration
  • Allows only the necessary fuel to flow to the engine, automatically adjustable
  • They have a tester 4G that’s been running for over a year nonstop, under pressure
  • Over a decade worth of pump time if you’re running for about 2 hours a day
  • Filters down to 2 microns! That’s crazy small!
  • Compatible with a number of aftermarket fuel filters (not just massive semi ones like some of the competitors out there)
  • A demand flow system that constantly refilters and recirculates excess unneeded fuel, instead of shooting all excess fuel back into the tank (like some outdated competitors)
  • AirDog uses synthetic brackets that will not rust, an upgrade over many other options out there
  • Steel brackets are available too if that’s your jam, but the synthetic brackets are great too, and we highly recommend them. And who doesn’t like options?
  • Some customers are claiming that with proper maintenance, these pumps could last over 2 million miles! That’s insane quality.
  • The best diesel fuel filtration system on the market just got even better!

Review of the AirDog II 4G

In order to understand that true upgrades that the 4G motor brings to the AirDog 2 fuel filtration and preporator for diesel engines, you must first understand some of the biggest issues diesel engines suffer from that lead to unnecessary wear and tear, loss of power and torque, and a huge uptake in DPF regens.

Not all diesel fuel is created equal.

Nor gas for that matter.

And beyond any contaminates that might be in your diesel fuel when you have to gas up at unfortunate times in poorly stocked areas, there’s always going to be some water and air that gets mixed into the batch.

First, that’s kind of just the way things are. And even if when you fill up your tank you somehow managed to get no air in, which is pretty wishful thinking if I do say so myself, even then, overtime in your fuel tank, as the diesel is sloshed about, guess what happens: aeration. And yes, it’s “aeration,” not “airation,” which is not a word. Get it right!

This process of mixing a gas, like the air we breath, into a liquid is often done deliberately. Just think about every carbonated beverage you’ve ever had in your life. Yeah, aeration.

However, aeration is pretty horrible for your engine. Look, your engine already has a proper mechanism for getting air in with the fuel: your whole intake system! And when you’re adding in more from your fuel injectors, not only can you throw the whole fuel to air ratio off, which means you’ll be wasting fuel and possible causing extra damage to your cylinders and pistons, but worse than that, you’re more likely to increase wear and tear on your fuel injectors themselves!

Fuel injectors are designed to shoot fuel into your cylinders, not air!

And worst part of it is that when you add air into the fuel, it actually can significantly increase friction while simultaneously decreasing lubrication. In fact, with an improper mix of the two, you could see upwards of 55% more contact between machined parts, which obviously leads to increased wear and tear. Over time, this will cause your injectors to become warped or to fire off more fuel than necessary, further increasing the issue.

And of course all that added fuel has to go somewhere: your exhaust. This leads to a loss of power, fuel efficiency, and an increase in DPF regenerations over time.

Again, your engine is a huge system of interconnected parts. We all know this. And if there is an issue in one area, like your fuel pump, it is going to translate into issues throughout the system.

What fascinated me about this product was the great demonstration videos AirDog has done to show just how this system works and just how much air and vapor you might have in your engine without a proper fuel filtration system like the AirDog II 4G.

Speaking of vapors, the AirDog is going to eliminate them from your engine too. When we speak of vapors, we are really talking about pressure in your fuel tank, and I know, this is getting complex, so here’s the quick version:

Vapors, Air, Water, and other contaminants in your fuel = bad for engine.

Vapors actually start to build up in your fuel tank due to something called cavitation. This is basically when the pressure on one end of the system causes rapid and sudden changes in another, forcing the formation of vapor in areas of relatively low pressure, such as in your fuel tank and lines.

Now why does this happen? Again, see those air bubbles and water in the fuel above. Without a proper filtration system on your diesel, the build up of air especially in the lines is going to cause pressure issues. Ultimately, this just exacerbates the issues, as it leads to the formation of pressure differences throughout the fuel system that cause the formation of vapors that further cause issues with your fuel system. Ahhh!

The cycle just keeps getting worse.

Introducing the AirDog II 4G

And then Air Dog shows up to save the day.

This state of the art filtration system first removes the water via the first filter. 99+% of H2O gone from your diesel fuel. But that’s just step one. Next, the fuel moves into a second filter capable of filtering out anything down to 2 microns in size. That’s crazy small! The second filter part on your Air Dog pulls out all the air too. And now you are basically only sending pure diesel fuel to your engine, instead of water, air, vapors, and any other contaminants.

Air Dog II 4G Cross Section Diagram

But wait! I didn’t explain the vapors part?!

Oh, I know. I was getting to it.

Here’s the deal: when you filter out all the water, remove all the air, and prevent any contaminants from reaching the engine, you prevent those extreme and sudden pressure changes that were--that’s right--due to those issues in the first place. In other words, no more cavitation! So no more vapors.

Now you’re still going to get aeration in your tank from the fuel moving around when your vehicle is in motion, but now you’ve got an Air Dog to filter that air out, my man!

The 4G Takes it to the Next Level

Now most of what I’ve already mentioned was true for the O.G. Air Dog and the Air Dog 2, so what makes the Air Dog Two 4G so special, you might be asking?

First, the 4G stands for 4th generation for the motor. This new motor is simply stunning. Not only is it insanely durable and built to last over extreme duration, but it also is incredibly quiet. And I know, the decibels a fuel pump motor puts out might not be that big of a deal for some of us, but it can be annoying on your show truck, no doubt. This new motor is so quiet that when properly mounted, from next to the truck, it may not even be audible at all. It’s that silent.

But for me, the big innovation is the low pressure return and refilitration cycle. And those might sound like really fancy marketing terms, so let me explain what makes them so great. First, many (most of the competitors in this field for instance) products out there simply spit out any excess fuel directly into your fuel tank. And if you’ve read this far you know how silly that is. That only adds air to the equation via--you guessed it--addition aeration and agitation of the fuel. And it is simply unnecessary.

We get it. When you’re designing your first fuel system, you just want to filter solidly. It makes sense. But you’ve got to iterate and innovate, people! And that’s exactly what Air Dog and Diesel Rx have done here.

Instead of just sloshing the excess fuel back into your tank, they’ve figured out an ingenious method of recycling and running the fuel back through the filtration system again!

That means the fuel going to your fuel line is often running through both filters twice! Talk about filtration power. It’s brilliant!

Now of course you need to be able to send the air and any excess beyond capacity back to the tank, but that’s where the low pressure valve comes in. This baby slows down and slowly leaks the air and excess fuel back into the tank, causing a slow trickle instead of a crazy splash into your fuel tank.

Again, these are just epic innovations that the other guys just can’t stand up to just yet.

And all of this works because of the great design of the Air Dog and tireless hours of dedication from their stellar team. And it is this hard work and smart design that has made the Air Dog the success that it is today.

And one of those reason, as described above, is that the AirDog 2 is a demand flow system, meaning that it only sends the fuel that the engine requires to the engine. It self regulates. Whatever else is in the Air Dog is recirculated and constantly filtered again to make it as pure and smooth as possible--way more filtration than anyone else on the market, especially products that just shoot excess fuel back into the fuel tank, which leads to increased aeration of the fuel in the tank, which is obviously bad for the fuel.

I know. Who would have thought I could go on and on about a fuel filtration system like this, but here at Midwest Aftermarket, we do the research for you to help you select the best product for your truck. And that’s the truth. We’d sell the other guys if we thought they stood behind their product like Air Dog does. But the truth is: the AirDog II 4G is simply a superior product, as of the time of writing. The competition needs to catch up before we’ll give them the time of day.

And if you need help selecting the right Air Dog for your ride or have any tech questions, just pick up the phone and give us a call at 1-800-951-3955. Our friendly customer service team is standing by, right here in America, waiting to help you find the perfect product for your diesel.

We hope this review of the AirDog II 4G has been helpful for you. Get yours today!


A Quick Video Demonstration from AirDog of the AirDog II 4G (you may need to turn up the volume some for this one)

AirDog® Comparison. What is the difference?

And Here’s an Install Video from AirDog for a Duramax

Our Promise of Exceptional Service and the Lowest Prices on the Interwebs

When you’re ready to order your Air Dog II 4G, we hope you’ll get yours from us here at Midwest Aftermarket. We only promote products we believe in and sell them at the lowest prices, shipping quickly to you for free if you’re in the lower 48 states. We have an excellent return policy and strive to get you the right product in perfect condition the first time.

What are you waiting for? Give us a call or place an order directly through our website. We’ll get your product out to you ASAP so you can enjoy your vehicle and make it your own. If you have a vision of what your truck or Jeep could be, let us help you achieve that image, that goal. We put aftermarket right at the tip of your fingers on your smartphone, web browser, and even via various apps, making ordering the parts you need super easy. Let us help make your aftermarket dream possible. Let us help you build your dream machine. We want you to drive the truck or Jeep of your dreams right now. So when you get it installed and love it, make sure you share us some pics on social media so we can live vicariously through you. Because we too are aftermarket enthusiasts, truck and Jeep owners, who love and own many of the products we sell. In other words, we don’t just work aftermarket--we are aftermarket.

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What pump do I need for my truck?

AirDog ® and AirDog ® II 100 units are recommended for up to 500 horsepower. AirDog ® 150 and AirDog ® II 165 units are recommended for horsepower up to 1000. AirDog ® II 200 units are recommended for anything that exceeds 1000 horsepower.

What kits will require dropping the tank or installing a suction tube?

All AirDog ® 150, AirDog ® II 200 Systems and AirDog ® II 165 Dodge Systems. Any truck that is equipped with an in tank fuel pump will require a suction tube or module upgrade kit.

If I daily drive my stock truck will running an AirDog ® 150 or AirDog ® II 165 4G hurt anything?

No, it will not hurt anything. With the Original AirDog’s High Flow return all excessive fuel not being used by your truck will be returned to the tank. When running the AirDog II 4G the Demand flow only allows the pump to send what fuel is needed to the injection pump, and all other fuel is recirculated internally in the base returning it to the suction side of the pump.

What is the difference between and AirDog ® and AirDog ® II 4G?

The AirDog ® II 4G aside from having the adjustable regulator, the pump and base assemebly are designed different internally. The pump assembly has a Dual Inlet design allowing more fuel to flow into the Gerotor, this allows the pump to increase volume without having to work any harder. The base on the AirDog ® II is also much different. Internally the fuel is redirected through passageways after being pressurized, this allows less fuel to be returned to the tank and more fuel to be held in the filters for a true “On Demand” system. An intermediate shaft was also incorporated to completely separate the electric motor from fuel path along with an additional two bearings to reduce drag and increase reliability and lifespan of the AirDog ® II 4G.