[markfuga]

I answered this question recently in personal email so I researched the topic and gained more knowledge of the Air Dog system than I needed to know. Here's what I know about it and invite anyone to help correct any inaccuracies.

The system IS designed for the 99 to 03 engines.

The Air Dog pump/filter setup is circulating fuel from and back to the tank at the main housing. It filters and de-aerates the fuel within the main housing and then sends the "cleaned" fuel out to the engine at 70PSI (regulator is in the main housing). The system is designed to work with the configuration of the 99 to 03 fuel system which is a "dead head" design. Fuel is sent to the engine at 70PSI, enters at the back of the heads and only leaves the engine through the injectors. I believe the system is re-using part of the original 99 to 03 lift pump to distribute the fuel (could use help here; I don’t know how it distributes the fuel on top of the 99-03 engines).

Adapting the system work on the first generation Powerstroke will require fabricating your own distribution lines on top of the engine to the rear of the heads and plugging the return holes at the front of the heads. Fuel does NOT circulate through the injector fuel rail and back to the tank (regulated return). Fuel sits in the fuel rail at 70 PSI and exits the heads through the injectors.

The only way to change it to a "OBS style regulated return" would be to remove the regulator from the main housing, which I did not see as an option from the reading I did. You would need to contact Air Dog to determine if that's a possibility.

Attached is the picture from the Air Dog site with my markups showing how it works. Sorry if it’s too small to read.

 

[markfuga]

Dave,

Are you saying the regulator can be removed from the Air Dog housing or is there a model that doesn't have the built in regulator?

If you setup the engine with a typical regulator, and still had the regulator in the Air Dog housing you could end up with a "locked up" system where the pressure is stuck between the two regulators.

If the regulator on the engine was set to a lower PSI than the housing it could work, with the housing regulator acting as a "fail safe" against excessive PSI (not to exceed 70). Not a way I would set it up but it could work.

hopefully guys that have installed the system on an OBS will chime in.

 

[markfuga]

Thanks MJ, based on the drawing you supplied, my understanding of the Air Dog is 100% correct. In a nutshell, the Air Dog completely replaces the pump and filter assembly in your picture. Only one regulator exists (in the Air Dog), fuel is sent at 70 PSI to the engine, the installer needs to fab a distribution system on the engine to the heads. Wherever the Air Dog is installed along the frame rail is the same location where excess fuel is returned to the tank.

This is a SD "dead head" design where fuel is "regulated on the supply" versus the OBS which is "regulated on the return".

 

[markfuga]

The SD (99-03) trucks are not "regulated return" systems, they're regulated on the supply. From all the reading I did on the Air Dog it's a "regulated on the supply" which makes it ideal for the SD trucks. I know people adapt it to work on the OBS but I don't know the specifics of how they do it. My guess would be to make their OBS a "dead head" by plugging the front return holes. The other option is to add another regulator and have a second return line but that's operating outside the design of the unit. These are my findings based on reading research. I would need to call the company to get further information, but since I'm not trying to install an Air Dog I'll let the OP make that call.

 

[markfuga]

Sounds like I need to step out of this thread because I'm not helping the OP get the answer to his question.

MJ, if you have experience installing the Air Dog then please explain all the steps to properly configure it on the OBS engines. This will help the OP, others and myself.

 

[markfuga]

I don't believe you're wrong at all. I believe we're both saying the same thing, just a little differently and using different semantics. I agree the Air Dog is an inferior choice and I would also not suggest using it. I tried to explain to the OP how he could configure it for use on an OBS truck, which I believe is:

1. mount on frame with return from Air Dog housing back to the tank
2. run supply line to engine and make your own "y" to distribute fuel
3. plug the return holes at the front of the heads
4. (not mentioned yet) Bleed the hell out of the system before plugging heads

Like you, I have no actual experience with it, so my suggestions are based on my reading of it. During my research I didn't find any threads with a good explanation for configuring in an OBS truck so that leads me to believe very few people have done it.

 

[markfuga]

Not a waste, but not the best way to do it. As MJ stated, you'd be better of selling the Air Dog to someone that can take advantage of it, and you might make a few dollars in the process if you got it at a good enough deal.