Air dog
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Tuned
Joined: Aug 2005
Posts: 274
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From: Seattle, WA
Air dog
I have a 1997 f350 7.3 turbo diesel. I just put air dog on my truck and I think I might have an issue. It runs now and I can easily get 85-90 mph out of it but my issue is I only get 30 psi fuel with air dog. I installed air dog myself from a kit for a 99 and up on my OBS. The only parts I could from kit was pump itself, everything else useless.
what I did was remove mech. Pump and block off hole with freeze plug. Remove water sep. I made my own y-block with pres. Guage and lines to feed the backof heads ( did it without removing down pipe). Then tied y-block into factory feed line. For the return line I used "T" connector to tie return lines together to old return line. Where I am thinking I have problem is the airdog has its own built in pressure return that is tapped into tank filler neck. Should I have just tied return lines on front of heads together without connecting to factory return line????? Am I getting too much " return "and not building proper pressure. No matter how much I turn up airdog press. Adj. It does not increase pressure to injectors.
what I did was remove mech. Pump and block off hole with freeze plug. Remove water sep. I made my own y-block with pres. Guage and lines to feed the backof heads ( did it without removing down pipe). Then tied y-block into factory feed line. For the return line I used "T" connector to tie return lines together to old return line. Where I am thinking I have problem is the airdog has its own built in pressure return that is tapped into tank filler neck. Should I have just tied return lines on front of heads together without connecting to factory return line????? Am I getting too much " return "and not building proper pressure. No matter how much I turn up airdog press. Adj. It does not increase pressure to injectors.
Senior User
Joined: Nov 2004
Posts: 173
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From: Lakewood, Washington
What are you using for a fuel pressure regulator? I know on most set ups the fuel will exit from the front of the heads, and run into a fuel pressure regulator exiting into the return line going through the fuel selector valve, and back to the tank that is in use (assuming you have dual tanks). Have not heard of a system that plumbs into the factory filler neck(s).
You may need to remove one of the pressure regulators it looks like. The air dog looks like it has a built in regulator on the pump assembly. I would not use the filler neck adapter for return fuel.
You may need to remove one of the pressure regulators it looks like. The air dog looks like it has a built in regulator on the pump assembly. I would not use the filler neck adapter for return fuel.
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Tuned
Joined: Aug 2005
Posts: 274
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From: Seattle, WA
I do not have any regulators on system other the the internal one on airdog. It says right in instructions to run excess pressure line of airdog right into filler neck. They even supply a custom piece to splice into rubber filler neck part.
Senior User
Joined: Nov 2004
Posts: 173
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From: Lakewood, Washington
I see the Air Dog runs a "fuel preporator" that looks to eliminate air from the fuel, and then sends that "dirty" fuel back to the tank. I don't think that is the same as a truly regulated return. The 99 and up 7.3 were deadhead fuel systems and not regulated return like the OBS. Of course I'm sure many have modified to regulated returns.
The other thing to consider is our filler necks run 2 hoses with the outer hose as a vent unless you have modded this already. You can drill into the filler neck just inside the cap to install a fitting for return fuel. I had to do this for my auxiliary tank hose into my front tank.
I hope someone already running this system in their OBS will give you some help. I'm running a Bean's system, so hard to visualize how the Air Dog is set up.
The other thing to consider is our filler necks run 2 hoses with the outer hose as a vent unless you have modded this already. You can drill into the filler neck just inside the cap to install a fitting for return fuel. I had to do this for my auxiliary tank hose into my front tank.
I hope someone already running this system in their OBS will give you some help. I'm running a Bean's system, so hard to visualize how the Air Dog is set up.
Hotshot
Joined: Dec 2005
Posts: 10,253
Likes: 7,687
From: Chino Valley, Arizona
99 and up are single tank trucks so putting it in to the filler neck is okay, your truck is dual tank and therefore return needs to be plumbed into the return line so the tank selector can put the fuel in the tank it was removed from.
Lead Driver
Joined: Oct 2003
Posts: 8,476
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From: Madison, WI
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Tuned
Joined: Aug 2005
Posts: 274
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From: Seattle, WA
I did find problem. I do need to "deadhead" return lines ( I clamped of hose with vise grips and got 60 psi instantly ). I will get rid of filler neck return hose ( worst idea ever!) I will use existing return line for excess pump pressure that way I can use factory tank selector. Main problem it is sooooo simple too easy to overthink it.
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