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Improving Diesel Performance

Automotive April 10, 2014 Sonia








Installing the Airdog II Lift Pump for Improved Diesel Performance

By Tim Walton

The AirDog II is a fuel/air separation system combined with a high-performance lift pump that not only provides more fuel for performance-enhanced trucks, but also removes air, water, particulates and vapor to maintain optimal fuel flow and delivery. The lift pump serves to provide a high volume of diesel fuel to the injection pump, which is what increases the pressure before the fuel is injected into the engine.


By removing entrained air from the fuel it improves injection timing, increasing power and giving you a better fuel burn. Because entrained air and vapor are compressible, their presence in the injector delays the pressure buildup and therefore delays or retards the injection timing.

In addition, inconsistent air bubble sizes that naturally occur in stock systems produce an inconsistent volume of air entering the injector from injection to injection, which not only means retarded injection timing, but inconsistent retarded injection timing, which is even worse.

What does this mean to you? Getting rid of the air produces good results. It can help improve fuel economy while reducing exhaust emissions, giving you better throttle response and top end power. The better filtration provides optimal fuel system lubrication and can help give you longer injector life.

Here’s how the guys at Mobile Diesel installed the system.

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Down at Mobile Diesel Services they’ve installed quite a few AirDog systems and they prefer to drop the stock fuel tank rather than doing a bed-off installation. Even if you’re installing the AirDog in your driveway, it’s probably easier for a couple guys to drop the tank instead of removing the bed itself.

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Pre-assembling the bracket and AirDog setup is a good idea to confirm the best mounting location.

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If you’re doing this install on a rack, a transmission jack works great for supporting the weight of the fuel tank on a broader surface—as well as allowing you to lower and move the tank.

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Remove the clamps that hold the filler hose and other breather hoses from the gas tank.

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Unplugging and disconnecting the wiring and hoses that go to the fuel module is one of the trickier steps to this install. The top of the tank is not only hard to reach but also difficult to see.

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When you take off the straps that hold the tank in place, be sure to lift up on the straps to remove them from the notched side to avoid bending the straps, which would make them harder to reinstall.

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If you want to leave the tank on the transmission jack, centering it on the jack and strapping it down is a good idea. The tank must be stable for removing the fuel sending module.

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The top of the tank can be pretty dirty. It’s important to clean the area around the module before you start disassembly to prevent getting dirt or debris inside the fuel tank. The guys at Mobile Diesel use compressed air to do some of the cleaning.

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A retaining ring holds the module in place. Use a screwdriver and a hammer to spin the ring free so you can remove the unit.

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Since the guys ended up mounting the AirDog II outboard of the frame rail on this short bed pickup, they used the supplied spacer so the bracket clears the parking brake cable.

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When removing the module, be sure not to bend the fuel level assembly. Empty the diesel from the lower fuel cup.