I replaced my filters and did the blue spring and now my secondary fuel bowl fills really slow and I am getting mainly air coming from the HFCM no matter how many times I turn the key on and off. I've taken the cap off the HFCM multiple times now. I've replaced the filter again and even replaced the cap just to make sure it wasn't cracked and not sealing. Fuel does drain each time I take the cap off so some fuel is in there. My thought at this point is the spring valve that blocks fuel from going into the HFCM from the tank is damaged. Have you seen this before? Is there a good way to test it without taking the HFCM off the truck? Is it repairable or can you buy the clip? I will be taking the HFCM off tomorrow. One other think is the fuel filter doesn't seem to snap into the pump like I've seen on some videos. The notch on the filter does catch on the body and is in the correct position. I used Motorcraft filters. Tank is 3/4 full. Thanks in advance.

1st, make sure your wif plug isn't corroded, if it is, you need to replace it before moving on. Next;
Remove the lines to/from the tank and put air through the return line, see if fuel comes from the feed line, if so, do the next step, if not, your pick up is plugged.
Next step, reattach the two lines you took off, then disconnect the line to the bowl. Turn the truck on and see if you get flow, make sure you have a way to contain the fuel that comes out. If fuel flows, but slowly, your ficm is done. If it does not flow at all, just the pump is done. If fuel flows good, the restriction is in the line between the bowl and the pump.

I had a pump go, replaced it and a few months later, the fuel bowl quit filling. I put a new pump in and still got nothing. I then did the steps above and that led me to the hfcm not working properly (there's a valve in it that fails and cannot be replaced). I picked up a new hfcm ($400~ for a Motorcraft unit at O'Reilly) and tada fuel again.
It's a good idea to have a fuel pressure gauge in the cab so you can see a pending failure and save your injectors.

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1st, make sure your wif plug isn't corroded, if it is, you need to replace it before moving on. Next;
Remove the lines to/from the tank and put air through the return line, see if fuel comes from the feed line, if so, do the next step, if not, your pick up is plugged.
Next step, reattach the two lines you took off, then disconnect the line to the bowl. Turn the truck on and see if you get flow, make sure you have a way to contain the fuel that comes out. If fuel flows, but slowly, your ficm is done. If it does not flow at all, just the pump is done. If fuel flows good, the restriction is in the line between the bowl and the pump.

I had a pump go, replaced it and a few months later, the fuel bowl quit filling. I put a new pump in and still got nothing. I then did the steps above and that led me to the hfcm not working properly (there's a valve in it that fails and cannot be replaced). I picked up a new hfcm ($400~ for a Motorcraft unit at O'Reilly) and tada fuel again.
It's a good idea to have a fuel pressure gauge in the cab so you can see a pending failure and save your injectors.

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1. Why did you change your filters and do the blue spring upgrade? Was it due to a problem you were having, or was it just time for the change & you wanted to do the upgrade?

2. You're using OEM filters, correct? EDIT Just saw that you are...

3. OEM Blue spring kit?

4. You're bleeding the air out of the system and priming the secondary filter housing every time after you open the HFCM cap, correct? (cycle key on till you hear fuel pump shut off and then cycle key off - rinse and repeat 5 more times, then start truck).

-jokester

1. Replaced filters for regular maintenance. No issues at time.
2. Yes
3. No OME on Blue spring kit. Amazon purchase.
4. Yes, turn key on/off many times after opening lower cap.

 

1. Why did you change your filters and do the blue spring upgrade? Was it due to a problem you were having, or was it just time for the change & you wanted to do the upgrade?

2. You're using OEM filters, correct? EDIT Just saw that you are...

3. OEM Blue spring kit?

4. You're bleeding the air out of the system and priming the secondary filter housing every time after you open the HFCM cap, correct? (cycle key on till you hear fuel pump shut off and then cycle key off - rinse and repeat 5 more times, then start truck).

-jokester

 

If this is the valve you are talking about, it a light tension spring, and you should easily be able to pull it back to see if somehow it is attached to the seat. There are not replaceable, although I am getting a pair of failed HFCM sent to me next week to do a failure analysis on. I could pull one of the spring valves off if that really is the issue; I would be surprised if it is.

Pulling in air from the inlet side can have several issues. For me, the easiest way to determine if it's tank or connector related is to put diesel in a 5g container or even a 1g bucket and put a 3/8" hose in place of the lower inlet quick connect and into the container. Key-On and see how the secondary canister fills - it should be quick and no air once the diesel makes its way up through the line.

The o-ring on the drain plug and cord gasket on the cover can also be an issue.

With 3/4 of a tank, it is not a blown re-icing valve or a broken pick-up foot.

One of the HFCMs that I am getting had failed similar to what you are reporting, but it wasn't determined why it failed - why I'm getting it. A replacement HFCM fixed his.

 

I took the HFCM off and took off the side cover. There was a little grit in the main bowl and in the drain compartment. I don't see any visual issues with it. I think its easiest just to replace and rule it out as the problem.

 

FYI, this is a 2006 F350. I just purchased it just over a month ago. 95K miles. EGR Delete. Came with an SCT X4 tuner. Does anyone know if any gauge on the X4 will help diagnose?

 

The regulator/blue spring will effect pressure, but would not cause air coming up to it.

6 was talking about the return line to the tank, not up to the engine. That would pressurize the tank and would flow fuel out the also disconnected tank to HFCM.

 

That makes more sense blowing it back to the tank.

Could the blue spring cause too much pressure in the secondary bowl and caused the pump to run bad? Meaning at a real low pressure.

 

The lines heading to the tank can get pinched or critter bites, that def would let air in
do you have the long frame mounted tank or the rectangle at the rear?

 

Its the long frame mount.

 

Unless the blue spring mod got totally fracked up

get a clean container with fuel in it and stick a 3/8 clear line in, connected to the suction of the HFCM
if that tests good, then
connect the hose to the outlet of the HFCM and plug / cap the return line at the HFCM -- pulling fuel thru the original suction here
fuel should run clear from the pump
the pump should run 20 seconds at each key on

 

FYI, the blue spring is a return Regulator, so it releases pressure once it builds up enough (should be 65 psi). It does not regulate pressure from the pump.

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FYI, the blue spring is a return Regulator, so it releases pressure once it builds up enough (should be 65 psi). It does not regulate pressure from the pump.

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After @TooManyToys informed me that I didn't understand your test in your first post I put the HFCM back on the truck and did it. I got fuel from the tank after blowing air in the return hose. When putting a hose on the output of the pump and cycling the key 6+ times I still get lots of air and hardly any press. Here's a link to the video I made of the test.

I'm picking up a new unit from O'Reillys tonight. Hopefully that's all that's wrong.

Do you think its just the gasket behind the plate on the HFCM? I didn't remove that when I originally replaced the filter. I didn't even open the WIF plug.

 

That's a ton of air. Since you have the option of getting a replacement HFCM, before doing that, I would pull the drain plug to see if the o-ring is OK and the plug not severely corroded. That can be a major factor.

 

The other test you can do is what Hydro mentioned. Put a half-gallon of fuel in a container and put a hose on the input as well, as you did on the output. That way you know you are getting good fuel into the HFCM, and not an issue with the line which runs tank to HFCM.

 

I don't hear your fuel pump running at all...

-jokester

 

Damn, I had the volume off while it ran.

SS, does it have the normal running sound, and the cell mic just did not pick the sound up?

 

pump is running.

 

Good vid @slap3shot, but you must plug the return line from the engine(top line) else the pump will suck air back thru the return -- the return is internally connected to the pump suction to recirculate fuel in the normal setup

connected this way (return capped) the test will confirm the suction and return to the tank -- the fuel should flow clear after a couple of key on cycles
if there is still air then cap the return to the tank -- this will eliminate that line
if still air, then look at the o-ring on the filter cap -- it is possible to get it in the wrong slot
the o-ring should be in the top(next to the cap) slot and the cap should only be tightened down to the thread stop
no need to crank down on the cap, grease the o-ring

 

Good vid @slap3shot, but you must plug the return line from the engine(top line) else the pump will suck air back thru the return

ehhh.. well, that sucks. So my test is bogus? Doh.

 

Did the tank by-pass test. Same result. The o-ring on the plug looks okay.
https://youtu.be/2q2Cl21IcOg

 

Gots to cap the return ports on the HFCM

 

Ford in their wisdom made a recirculation path in the HFCM to help heat the fuel at cold temps, if the internal thermal valve is not sealing well then the test will fail as you have done it

capping just the engine return can still suck air from the tank if the fuel level is low -- the duck bill check valve on the return may not seal very well

doing the test with half a tank or so, would eliminate any in tank air problems and limit any air to the external lines or fittings

making sense now?

 

Here's my test plugging both end of the return. Fuel looks good in hose now. Air leak coming from fuel regulator? How much pressure should I expect out of the pump? It was flowing good but I would say it had low pressure.

 

Loving the spark plug hose stoppers

one more test -- connect the return line to the tank and see if the fuel is still clear
you should have a good flow from the hose and if your hose is secure, about 100 psi available

you commentated about air originating at the upper fuel filter -- yes it can come from there
if the return line has leaked back to the tank, then air can be drawn down that line to the pump when doing a test with the filter cap off
there is an o-ring on the stand pipe in the upper fuel bowl that should hold the return fuel, but it can get lost or just not seal good

so - doing the fuel flow test that we recommend can sometimes be misleading if the return fuel leaks off
air would be pushed back up the filter inlet, causing an incorrect diagnosis

 

The recirculating valve doesn't close until the return fuel is over 80ºF. The range is fully open at 50º, fully closed at 80ºF. So probably where ever you are, it's going to be open.

The goofy thing is, every time someone has checked HFCM fuel flow at the canister with the cap off, it's had the potential to do the same, draw air down the return line from the bleed hole at the top. But yet we see fill and no bubbles.

 

I didn't see your post until after I had everything connected up. I'm a little beat tonight to do anymore tests. I'm going to pickup a new fuel regulator seal tomorrow and give that a try. That's the cheapest part of this hole thing anyway. Hope that's it.

What is the "Stand Pipe" that you mentioned?

O-Ring

 

When I tested my '06 in the fall, the air in the return line thing bit me -- took a while to figure why it was sucking air -- about that time @TooManyToys made a vid showing the insides of the HFCM, then I understood why plugging the return worked

20*F outside right now , so not inclined to pull my fuel bowl apart to figure the fuel return path -- and sometimes why the fuel flow test without a filter works and other times does not

 

There is a direct path for air to enter the return at the little vent hole in the filter bowl, just above the pressure regulator

I suppose if the duck bill valve in the tank is holding and the return line is full -- that may explain why the test works most of the time
the fuel return line holds enough that the fuel bowl fills and the test is ended, before the line has a chance to drain down

if the return drains down, the pump likely will suck air -- this can be proved by un capping the return line from the engine with your setup
air should soon start being pulled into the pump -- since the return is connected to the suction

I proved this theory on my '06 this past fall -- when checking how low I could draw the tank before running out of fuel

 

You're right; plugging the return port on the HFCM is the best method. It takes out the variability.

I tried to figure out if there would be enough residual fuel in the line from the filter canister to the HFCM to refill the canister without the air getting to show bubbles.

I'm still worried about is during all this, and there wasn't a voltage check at the HFCM while it was running. Although at 95k miles, none of this should be happening.

 

Many thanks for all the help, saved me from buying a new HFCM for $400. I don't think it is the problem anymore. I've ordered a new spring kit and will try different o-rings first. I borrowed a fuel pressure tester from O'Reillys to check it before I try starting the truck again.

 

Many thanks for all the help, saved me from buying a new HFCM for $400. I don't think it is the problem anymore. I've ordered a new spring kit and will try different o-rings first. I borrowed a fuel pressure tester from O'Reillys to check it before I try starting the truck again.

Don't rule out the hfcm just yet. That check valve in the hfcm, that let's air in, does fail and stops fuel from moving up to the bowl. The good news, when my hfcm failed this way, I didn't even get air, there was, simply, no fuel past the hfcm (towards the bowl).
At this point, I'm guessing you fubard the fuel line at the Regulator, you missed something in the blue spring kit, or scared the mating surface of the Regulator to fuel bowl.
Depending on which one, you're still looking at spending some money to fix it.
You didn't use any sealant on the Regulator did you?

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Watch the vid that @TooManyToys made, it is pretty in depth on the HFCM
the link in in his signature line

 

I've watched it but need to watch again.