2004 f250 6.0 / using the Motor-Craft FD-4616 fuel filter kit.

I have air sucking on the frame rail fuel filter, its driving me a little nuts. I changed the filter, tried two different filters (both new) and new o-rings and it is still doing it. Truck will start fine, but then will die after 30 seconds and a fuel icon appears in the dashboard when it dies.



Any ideas ? I recorded a youtube video, so you guys can see, what is the best way to diagnose, where the air is coming from ?

 

Are you sure it is air being sucked in, or could it be a bad pump. They are easy to change out.

Might want to remove the manifold cover and clean everything in there.

Is the water drain plug in good condition? If it is just a plug with an allen wrench connection to remove, there is a much better plug to replace it with..

Pump: 6C3Z-9C407-AA - However, Ford no longer sells pump by itself (and the entire HFCM is $350)
PFP58054 - Parker-Hannifin ($117)

Updated water drain plug - 6E7Z-9C082-A

 

I today I did some testing from the fuel tank side, in out-flow I disconnected that and connected a tube to a glass container and observed it and there was definitely air coming back, then I totally disconnected the in-flow from the fuel tank and isolated the tank and there was still air coming back...

so I did replace two fuel injectors a while back, would it be the manifold cover or the copper washer of the fuel injectors ?

after replacing the fuel injectors it ran fine, then I upgraded to the blue spring, and it ran fine, then I replaced the fuel filters and that's when this problem started, I am using the MOPAR Ford recommended filters...

So you are saying that the manifold cover could be introducing air ?

 

I don't know what "MOPAR Ford recommended filters" are. They are not OEM, and using OEM filters is best,

What do you mean "air coming back"? I can't picture what you are saying.

When you detected air in both of the tests, which direction was the flow (from where to where)?

... And yes, air can be introduced by a bad primary filter seal, a bad o-ring on the drain plug, or even the manifold cover IIRC.

 

I disconnected the return fuel line (from the primary filter housing) and put that into a growler, see video and then cycled the key.


re: the drain plug, that seems to be stripped a little bit, I used both the original plug and the upgraded one, and it don't seem to make a difference, I mean when I screw it in I make it snug, but not too much pressure since it is stripped already, could that be the issue ?

is there any way to test for the drain plug ?

I mean when I put key on, ignition off, I put my palm over the (original drain plug) and press to close off any air, to see if it was sucking air against my skin and I didn't feel air against my hand, the air noise continued ?

Are there any videos on youtube about air leaks from the manifold ?

 

The most common places for air to be sucked in are:

1. bad o-ring on the primary fuel filter cap
2. the drain plug not sealing
3. The fuel tank pick-up tube foot (a part can fall out causing it to suck air at 1/4 tank level or so).

The manifold cover can also be an issue, but less likely (would need to have a leak in the perimeter gasket and an internal one).



If you the drain plug is stripped, you will need a new manifold cover.
Part # 6C3Z-9B249-A

I would check the primary filter cap o-ring.

When you returned the fuel flow to the bottle, I would have placed the return line discharge below the fuel level to avoid agitation by the fuel free-falling into the liquid level.

 

1) I don't think it is a bad o-ring on the primary filer, I tried 3 different ones, all were new and even the older one - and the problem persists, also tried 3 different type of primary filters and that didn't work.

2) I put a bunch of teflon tape around the threads and put the drain plug back in there pretty tight - problem still there.

3) the fuel tank is like 3/4 way filled, so even if that tube fell off, it would seem to be "ok"

when I did that isolation fuel test, I noticed a lot of air bubbles flowing through the tube (even if it wasn't under the fuel level) in that growler and I noticed when I was cycling the key, that there was like white fumes coming out, maybe from the engine cycling ? not sure if that is normal or not...

I hate to spend even more money of this crap truck and only to find out, that is not the problem I already replaced the fuel pump in the primary fuel area and with the old fuel pump, the problem was the same, so it wasn't the fuel pump at all.

Question: is there a way to find out if the air is coming from the manifold ? some kind of test ?

Is there a for sale area on this forum :-) lol

 

The next step I would do would be to fill the secondary fuel filter bowl (w/ the cap off and filter out) by having someone turn the key to run (no cranking) while you watch. Check to see if you have air bubbles in the liquid as the fuel filter bowl fills up.

 

If there are bubbles, what does this mean ?

 

The upper fuel filter system has an air bleed system. I was just wanting to determine if it was working preventing air from getting to the fuel injectors.

If you are confident in all of the things I have mentioned, then it must be the fuel pump. You can replace it separately (no need for a whole new HFCM).