Join Date: Apr 2008
Location: Moyock, NC
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No, Mitch is correct. The AD2 is a great pump, easy to install and will fuel whatever injectors you want to throw at it.
The concern is the dead heading in the heads and possibly starving the rear most injectors of fuel. Stock setup, fuel is pumped through the filters and then to the heads. It stops there at the back of the heads. Now the fuel pressure regulator (which is in the small filter housing), is nothing more than a spring and a plunger seat. Once the pressure is reached that is determined by the spring, that plunger will crack open and the excess fuel is diverted back towards the tank. So it is recirculating the fuel before the heads.
The regulated return. On the back of the heads, there are two plugs in the same spot as the fuel inlets on the front of the heads. By attaching lines to those rear ports, then to an adjustable regulator and routing the return to the tank via the return line at the fuel bowl, you are constantly flowing fresh fuel through the heads and eliminating the dead heading. What I mean at the fuel bowl is you put an oring in the fuel pressure regulator to prevent it from opening, remove the tank return line from the filter housing, cap off the fuel bowl filter where you removed that line, connect your adjustable regulator return line to the tank return line you just removed.
Ideally with an AD2, since it is regulated at the pump, you would want to install the regulated return as described above but omit the adjustable regulator and just run the lines. The AD2 has an adjustable regulator built in.
The regulated return is basically insurance for your injectors or the crossover/return if using the AD2.
It all depends on what you feel comfortable with. The AD2 alone is a great choice and an upgrade. The twin pump setup is another great choice but requires a little custom work and allows for redundancy. The sump is really not necessary at all, but it helps with fuel delivery by allowing the pressure of the fuel above it to force it towards the pump instead of the pump sucking, then pushing.
Here is where I am with my truck and the plans. It is a daily driver. Just finished head studs, and installed 190s in it. Installed the upgraded Ford spring in the fuel pressure regulator. My pressure is at 68psi normal cruising and idling. Half throttle for passing it drops to 60psi. I am running a completely stock setup for a fuel system other that upgraded banjo bolts. I would love to install an AD2 and the crossover/return line. But for the price of it all would be around $1000. The Raptor pump and the regulated return would be about $800 and will achieve the same results with the ability to run on just one pump should the other fail. The AD2 also has the added benefit of deaerating the fuel. Crap, I think I just convinced myself to go with the AD2 and crossover/return just for the fact that it remove the air from the fuel helping and contributing to the longevity of those very expensive injectors.
Wow, that was pretty long winded...but i hope you sort of understand. If not, just get and AirDog2, it is easy to install and will give you plenty of clean, air-free fuel.
05 F250 4x4 CC, 9.5" Rize/Icon, 38" Toyos, 20x12 Pacers, 5" MBRP, AFE stage 2, Cass 190s, Powermax, ELC w/filter, RCD EGR delete
04 Excursion 4x4, vacation bus
Project 1979 F250 6.0 powered in progress