Foolish_Mortal

Fuel is making it through from the front tank :/
it just kinda falls out of the rear tank, doesn't seem to have anything pressure wise.

I have been driving the truck on the rear tank mostly, 2 days ago getting on the interstate it started cutting out so I switch to the front and all was well. Made it home, at night I switch it back to the rear tank to see if it would run and it did great for a day, then at the end of the day it started cutting out again so I switched to the front, again it was fine.

Just call me Sean

iTrader: (1)

Stuck or sticking, or the pressure is too low on the rear pump.

Foolish_Mortal

would you lean more towards not enough pressure on the rear pump considering it was running fine while on the rear pump and then quit running on the rear pump?

I don't quite understand how the fuel valve could shut off the rear pump when it was running on the rear pump unless the rear pump lost pressure. :/

Foolish_Mortal

Ok, I pulled the switching valve,
Front tank seems to be putting out proper pressure from the fuel line, rear tank seems to trickle, plug in switching valve, fuel shoots through just fine on the front tank, rear tank is just a trickle. Although I don't understand why fuel is now coming out of both pressure lines even with the key off, and then continues even with the battery unhooked, the truck does run, I also suspect the truck is sucking off both fuel tanks or they were cross filling :/

5Rangers

The dribble is siphon action. Store the disconnected lines higher then the tank. The in tanks are volumetric pumps and need to provide a certain volume of fuel to the DFR so the high pressure frame pump will be supplied. Without the volume the frame pump cavitates, pressure to the fuel rail is reduced or non existent, the pump growls from loss of fuel and the engine stops running. If the high pressure pump continues to see cavitation it will eventually fail since it uses the fuel for lubrication and cooling.

Foolish_Mortal

I'm taking this as summarization that I should run it on the front tank till I get time to pull the bed and replace the rear in tank?

Thank for your response, especially on the dribble, I've done tons of fuel pumps and never ran into it before.

5Rangers

Correct.. There are 2 schools of thought. One says remove the bed and another says drop the tank. I follow the school of drop the tank since I have no friends. It is easily done when empty. Installing is a different story but is also easily accomplished with using ratchet type cargo straps to assist in raising and positioning the tank.

As a side note, the ford manual specifies no more the 5 psi of regulated air for testing the DFR. Hopefully you wont have any problems with it.

Foolish_Mortal

I also have no friends, but I do have this

which should end well

bobkyle2

You have me :hug: And i have lots of friends. Just drive it to Illinois, And we will change that bish. Ain't no way i'm coming to Mexicano :O


You could , just be a man and cut the bed open.

Orrr, Put like 30 or 15 electric inline pumps on it

Foolish_Mortal

I'll drive to illinois and let you and your friends change it

I thought of cutting an access hole but I really don't want to take a torch to my truck