I have a 2004 6.0, replaced the factory fuel pump with an Air Dog II, not long afterwards, it would run out of fuel at 1/4 tank. Gauge is not wrong as I pumped 8 gallons out of tank. I pulled the tank to check if anything wrong, every thing seems to be intact. I put up with this for a year and when the motor of the Air Dog quit working, I pulled the tank and put in a 3/8" brass pipe suction tube, goes all the way to the bottom. I ground the bottom of the pipe so it wasn't flat so that fuel can still enter in case the bottom of the tank was against the pipe. I replaced the Air Dog and now I am running out at almost 3/8 of a tank. I can only get 375 miles from a full tank until it runs out. Is the return line pushing so much fuel back into the tank that it is causing the fuel to foam? I have a fuel pressure gauge and it read 50-55 psi depending on the temp outside. When it acts like it is going to run out, the gauge fluctuates quite a bit. When it stalls, the gauge resisters 0 psi until its able to pick up fuel and then goes back to 50 and the engine starts and I can baby it home or to a station, I just have to stop gently and take corners very slowly. This is frustrating.

 

If it was me I would toss the Air Dog, put a stock pump on, and use that. Running out of fuel is a recipe for disaster with all of the injectors. What do you have that makes the stock pump unsuitable?


Brian

 

There's a plug thing on the bottom of the pickup in the tank that's been known to pop out and cause the truck to suddenly run out of fuel around 1/4 tank. Is it still in there? This guy found his lodged in the vent tube after it came out.
https://www.ford-trucks.com/forums/8...d-for-3-a.html

 

OP said he had replaced the stock pickup assembly inside the tank with a copper pipe, and his symptom got worse. So the lost valve idea probably isn't going to be the fix.

Brian

 

Unfortuantely AD2/FASS both have the "empty at 1/4 tank problem". The only sure cure is to install a sump and get rid of the drawstraw.

 

If you look at this
OEM FUEL PUMP SENDING UNIT 2005-2006 FORD SUPER DUTY 6.0L DIESEL #5C3Z-9275-BA | eBay
you can see the black screen and the reddish return.
I wished I have a better photo of the sender.
But if that little red valve is missing then you can get air. I would check and make
sure it is still in place. If not I saw a screen replacement kit so there must be
one for that valve also. The bad idea about the pipe to the bottom of the tank
is you will get any crap in the tank pulled into the pump. I would go back to a stock
screen/pickup and valve.

Sean

 

He's running a drawstraw that's sitting in the bottom of the tank and still has a pickup problem. Been there, done that, got the tee shirt, AND the PHD and STILL don't know why. The only thing that works consistently is a sump. It's more money but easier on the pump (AD, FASS, or stock). The only other solution is to drive with eggs under the go pedal with 1/4 tank or under so the fuel doesn't slosh.

 

Thanks for all your timely advice. I removed the black rubber thing and just ran a dip tube down to the bottom of the tank. Any thing that might get in the tank and drawn up goes thru the filter assembly before the pump if I remember the literature about the air dog. I make my own bio and filter it to one micron before it gets pumped into the tank. Been running it for 80,000 miles with no problems. I got the air dog cuz the factory unit quit working and at the time the dealer wanted about 900.00 for one and the airdog has filters that are way easier to change out. I guess the answer is the sump. Which one?

 

helman sump