If you look at the schematic on pg 53/28 www.powerstrokediesel.com/docs/EF_456.pdf. there's a one way valve locates in the HFCM that should prevent the upper fuel bowl from draining. That diagram is a little old, the newer HFCM do not use a fuel heater. I'm not saying replace the HFCM again, but I don't see anything in the schematic that would allow the upper fuel bowl to empty and bubble.


I ruined an HCM when I cleaned it out after a batch of bad diesel, saw junk in the filters and proceeded to clean the HFCM. I cleaned the gunk into the pump and ruined it.

 

That's what has me stumped. Being brand new you would think it wouldn't have issues. Still trying to chase it down. Thanks for your reply!

 

Double Post Deleted

 

Bump. Still looking for a solution.

 

OEM filter?
OEM HFCM?

fuel level ?

can't keep fuel pressure up

what Fuel PSI are you seeing?

 

OEM filter?
OEM HFCM?

fuel level ?

can't keep fuel pressure up

what Fuel PSI are you seeing?

OEM filter. HFCM is not. I'm over half fuel. Haven't been able to hook up a gauge to it yet. Waiting for a friend that is out of town. Blue spring mod as well.

 

So update. I filled the fuel bowl with clean diesel till it no longer drained back to the HFCM. Truck ran great for a few minutes then it was back to shuttering. Lead me to believe that the pump is drawing air from somewhere or it's not getting enough fuel. Dropped the tank and the only issue i could find was the pick up screen was ripped off. That couldn't possibly causing my problem could it? Considering the tank has 3/4 of a tank?

 

I gotta ask, have you ever seen any evidence of the pick up screen? Bottom of the tank, in the fuel filter? When I ruined my HFCM and replaced it, I had it replaced with OEM.

 

I found all of the pick up screen in the tank. The screen was partially hanging on the pick up tube. It broke completely as I took it off.

If your lines under the cab aren't connected correctly you will suck air and it doesn't take much for it to drain the bowl.

completely agree. I think the supply line was not on the tank all the way. When I removed the tank it came off too easy. So I reinstalled the tank today with a new pick up screen. As I re attached the fuel lines the supply line would not clip correctly. A little prying and I got it to stick. I pulled on it forcefully and it did not come loose.

 

If your lines under the cab aren't connected correctly you will suck air and it doesn't take much for it to drain the bowl.

 

Well I'm happy to report the truck is back up and running. As hard as it is for me to believe that the torn rubber on the pick up tube cause me to have fuel pressure issues the truck is running beautifully once again. I guess the fancy diaphragm serves its purpose. Thanks to all that took the time to comment!

 

Did this solve the issue of the fuel draining out of the filter housing? Do you have a part number for the pickup tube?

 

Long story short no. Truck ran great till about three weeks ago. I got brave and ran the tank low again. Filled the tank got about 5 miles down the road and the truck started running ****ty again. Got it home tried to prime it to no end. Dropped the tank and the bypass valve was missing out of the brand new pickup foot I just installed. Decided to slap a fuel sump instead of messing with the pickup tube anymore. Tried once again to prime the truck with no luck. There is a small rubber valve in the HFCM that should not allow fuel to drain back to the tank. I am convinced that the reason the fuel bowl drains back is because the pump is sucking air into the system leaving room in the housing. If you keep filling the bowl it will eventually stay full. That is until you kick the pump on again and add air to the system.

 

I am dealing with the same thing on a truck I bought about a month ago and only have been able to drive it for one day. I replaced the HFCM and the bowl will fill up but drain within a few seconds of shutting the key off. I am almost wondering if I should splice in a universal one-way/check valve in the supply line to see if that will do the trick. I also have the original housing and thinking about putting the new pump in the old pump housing to see if that works also. I will keep you posted if I come across any good solutions. This thing is driving me insane!

 

It would keep fuel in the bowl but from what I'm experiencing it would still have a lack of fuel pressure. I have my old pump as well so I may try the same thing.

On a side note I have a black o ring on the HFCM filter cap. I usually check the filters when I buy new ones to make sure it has a green one. I haven't been able to find the green o rings yet to eliminate that as a source of air being pull in.

I appreciate you taking the time to post. There are so many dead end posts on this topic.

 

I haven't had any experience with this first hand but remember reading that a bad injector o-ring will let fuel drain into the oil system. You can tell by the oil smelling like fuel and the oil level increase on the dipstick. Good luck!

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Tired my old fuel pump and there was no change. Guess I'll just have to order a new fuel pump and try it.

 

I'm having this issue now at 3/4 tank. Have the symptoms of a missing/broken pickup screen but not sure if this is possible. Im running an AD 165 4g. What was yalls solution?

 

I know this is an old thread, but did you ever fix this issue?
I have an 04 doing the exact thing. Can't figure it out for the life of me.
Replaced the hfcm, pick-up screen, filters, rebuilt fuel return on fuel bowl(all fomoco parts from the dealer) Still having the fuel drain back issue.