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bubbles in fuel bowl

14298 Views 38 Replies 7 Participants Last post by  upnorth the Bilge Rat
I get air bubbles in the upper filter bowl when I cycle the key.
I've cycled it and emptied the bowl several times and continue to get bubbles.
It also seems to fill really slow and stops filling after about 20 seconds.
It takes 2 to 3 times of cycling it to fill the bowl to the top.

The truck was running poorly, no power, no boost. I changed both filters did the priming sequence thing it started, ran for a minute and now won't start.
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You didn't mention the year of the truck or model

Bubbles can come from a damaged suction line or a restriction in that line
when you changed the filter in the HFCM, did you lube the o-ring? and turn the cap until it bottomed on the threads?

The fuel bowl should fill within 3 to 4 seconds

it is also possible you have a clogged inlet line at the fuel tank, some of the metal tanks liner would flake off

It is normal for the pump to time out in about 20 seconds without the engine running -- when the engine runs, the pump is continuous
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You didn't mention the year of the truck or model

Bubbles can come from a damaged suction line or a restriction in that line
when you changed the filter in the HFCM, did you lube the o-ring? and turn the cap until it bottomed on the threads?

The fuel bowl should fill within 3 to 4 seconds

it is also possible you have a clogged inlet line at the fuel tank, some of the metal tanks liner would flake off

It is normal for the pump to time out in about 20 seconds without the engine running -- when the engine runs, the pump is continuous
It's an '05 f-250 XL crew cab
Looks like it has a plastic fuel
tank but I didn't take a real close look at it.
I only lubed the o-ring with diesel as well as my arm and back
I did spin it on most of the way by hand

I wasn't sure what the pick up tube set up is. I'd assume I could take the bed off to get easy access to the top of the tank.
Dropping the tank is pretty easy as long as it is near empty
you can loosen the passenger side bed bolts and remove the driver side
then tip and block the bed up a little, to get to the fuel pickup

Ford picked a really dumb spot to put that lower filter for sure
you need to grease the o-ring and be sure it is not "twisted" on the cap
the cap will bottom on the threads, unless someone has forced it in the past -- there is a stop on the threads

I have seen the pickup foot in the tank disintegrate and lodge pieces inside the line
so if that is the case, you would need to blow out the line with air pressure
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Dropping the tank is pretty easy as long as it is near empty
you can loosen the passenger side bed bolts and remove the driver side
then tip and block the bed up a little, to get to the fuel pickup

Ford picked a really dumb spot to put that lower filter for sure
you need to grease the o-ring and be sure it is not "twisted" on the cap
the cap will bottom on the threads, unless someone has forced it in the past -- there is a stop on the threads

I have seen the pickup foot in the tank disintegrate and lodge pieces inside the line
so if that is the case, you would need to blow out the line with air pressure
I have over a 1/4 tank of fuel I don't have any means to empty it
I can use a cherry picker to lift the bed off.
In another forum we just had a well-respected member have his pickup foot disintegrate and clog the line. Those pickups are no longer being sold by Ford and the aftermarket ones come apart in a few months.

However, the air in the fuel bowl is often an o-ring issue as Hydro said, filter cap, drain port, or rarely the cover.
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I'll check the O-ring again and grease it up before I reinstall it. And I'll see what the pickup thing looks like in the tank.

Any thoughts on the fuel pump inside the hfcm do they die often?
As Hydro mentioned, you can remove all the bed bolts, except the ones nearest the tailgate. Those need to be loosened a lot, but can be left "screwed in" slightly. Then you raise the bed up by the cab and support it on 4x4 blocks. Essentially the bed will be tilted enough to provide adequate work space. Having the cherry picker is certainly handy, but if you don't want to mess with it for whatever reason, then the bed tilt method (with a jack) is fairly easy.

It is my opinion that the pump is a fairly reliable component. That said, failure of the fuel pump at reasonably high mileage is certainly not uncommon. On another forum, TooManyToys has some data on failures (mileage at which some have had failures).

Low fuel pressure can readily ruin expensive injectors. So can air in the fuel. For that reason, it is HIGHLY recommended for every 6.0L owner to install a fuel pressure sensor and gauge. The earlier you see issues, the better chance you have at keeping the injectors. Absolute minimum fuel pressure (at any driving condition) is 45 psig. I use 50 psig as minimum.

I carry a spare fuel pump. Not so much because they fail so often, but because they might and I don't want an early $1500 injector job. You can save some money and buy only the pump. Ford does not sell the pump by itself, but you can buy it separately in the aftermarket. That said, if you have had poor quality fuel, it might just be best to buy the entire HFCM. Crud from bad fuel can plug up things inside the HFCM.

Fuel pump (made by Racor who is the company that supplied the OEM fuel pump):


HFCM pump and Manifold (cover) - part # 6C3Z-9G282-C

Sometimes the pump will pull air in at the water drain plug (it corrodes or the o-ring seal deteriorates). It is best to upgrade the water drain plug with the brass one below (Part # 6E7Z-9C082-A):

The drain plug o-ring (stock and also the updated plug) are most likely Buna N material. Viton holds up much better. The o-ring size is 111 if you want to upgrade to Viton.
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I might as well post the link to the video I did on these if anyone comes across the thread and is interested. It includes the poll of failures.

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In the other forum, Eric had fuel delivery issues. There were a few problems, the blue spring kit had to be replaced, but the main issue was after 15 years, the foot in the tank disintegrated. That's been happening recently, probably due to age and the bio content in some fuels. As I mentioned, Ford does not supply these anymore, and on this and other forums the aftermarket replacements are not made from compatible plastic. The reliable alternative right now is to go to a sump.

A picture of what Eric found in his tank, and despite the cleaning and repair, still had issues probably due to debris in the feed line. A sump without the OE feed line has resolved the issue. He went as far as replacing the HFCM to no avail. A different issue due to bubbles, unless the foot is completely gone and the tank level is not where you think it is.

769116
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Thanks for all the info!
I'll tackle the tank first.
My gauge is showing over a 1/4 tank but I have no idea if it's accurate? I just haven't had the truck very long.
I may pull the hfcm out to look it over real good.
I did turn out the water drain plug, it seemed to be untouched. I drained it into a flat pan it didn't have any water.

I'm hoping the injectors aren't toasted but I won't worry about it until I can verify proper fuel pressure.
ARRRGGGG!
Finally got the bed off and fought with the blue fuel line until I won.
Two of the bed bolts wouldn't come out, I didn't want to weld a nut to them, so I cut the top to match a 1 inch socket and they came right out.
The pickup unit looks brand new the screen was clean. There was a little bit of debris some was black some was a copper or brass color. I tried to get some of it out with a little oil vacuum but not much sucked up. I did run a magnet through what I did take out and some stuff stuck to the magnet. Not sure what that indicates but I'll assume it's bad.
I'd guess the brighter colored debris got there through the return line.
I'm thinking...take the hfcm off inspect it, blow out the pickup and return lines and put it back together.
I have the scanguage2 here are some of the data from it, this was all with the engine not starting.
FLP=12
FMP=48
CVI=5V
ICP=1400 or more while cranking
FMP=48v KOEO
IPR=53.51
SYC=1
Ideas anyone?
A little more info on the truck. It is a retired "slope truck" It likely spent a lot of time idling during the winters on the Arctic oil fields here in Alaska. I paid $3k for the thing. Other then that I don't have much history. I don't have any reason to bulletproof it, I'm looking for cost effective reliability for something that won't be worked hard.
Any ideas would be awesome.
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In the other forum, Eric had fuel delivery issues. There were a few problems, the blue spring kit had to be replaced, but the main issue was after 15 years, the foot in the tank disintegrated. That's been happening recently, probably due to age and the bio content in some fuels. As I mentioned, Ford does not supply these anymore, and on this and other forums the aftermarket replacements are not made from compatible plastic. The reliable alternative right now is to go to a sump.

A picture of what Eric found in his tank, and despite the cleaning and repair, still had issues probably due to debris in the feed line. A sump without the OE feed line has resolved the issue. He went as far as replacing the HFCM to no avail. A different issue due to bubbles, unless the foot is completely gone and the tank level is not where you think it is.

View attachment 769116
Inside of my tank was much better then that one. very little black stuff but it had some copper/brass colored stuff.
Check the suction like from the tank to the hfcm for damage / pinched places
had a critter that bit my suction line and was not very obvious the damaged spot, only tiny puncture marks

You can substitute a 3/8 clear line in a jug for a suction setup to test if the bubbles go away

Some fuel bowls drain back(they are not supposed to) and when you do a filter out test, there may be bubbles
if you continued to run the pump the bubbles should clear up, would need a catch pan for the excess fuel tho
Check the suction like from the tank to the hfcm for damage / pinched places
had a critter that bit my suction line and was not very obvious the damaged spot, only tiny puncture marks

You can substitute a 3/8 clear line in a jug for a suction setup to test if the bubbles go away

Some fuel bowls drain back(they are not supposed to) and when you do a filter out test, there may be bubbles
if you continued to run the pump the bubbles should clear up, would need a catch pan for the excess fuel tho
Making sure I understand.
Run a clear hose from the hfcm to a container to check for air?
I could do that with or with out the filter installed in the hfcm?
You want to keep the filter in the hfcm, the line is just to eliminate the current suction line in case there is damage

you can add a second line on the return from the hfcm to the jug to eliminate the tank lines all together
the clear lines will let you see if the fuel runs clear or not - do this with the filters all in place
the 3/8 clear hose fits the connectors pretty well, but you still need a clamp
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3/8" on supply. 5/16" on return.
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You want to keep the filter in the hfcm, the line is just to eliminate the current suction line in case there is damage

you can add a second line on the return from the hfcm to the jug to eliminate the tank lines all together
the clear lines will let you see if the fuel runs clear or not - do this with the filters all in place
the 3/8 clear hose fits the connectors pretty well, but you still need a clamp
Ah Ha! now I got it!
I'm feeling less dense now
thanks. :)
The weather finally got better 4 days of constant rain, didn't feel like getting soaked.

.
I pulled the filter off again made sure the cap was spotless, greased the O-ring and hand tightened the cap until the threads were out of sight. Also removed the water drain plug and greased it's O-ring a bit and put it back together.

I ran a clear line from the fuel tank to the hfcm it has no air when I cycle the fuel pump. The line coming out of hfcm is loaded with air. The fuel flow coming out of hfcm is really slow, not much above a trickle

Should I replace the fuel pump?
The lack of fuel volume just doesn't seem right.
Did you tighten the filter cap till it bumped end of the threads? -- internal stop
air could be if you didnt fully seat the filter o-ring
or possible the o-ring where the pump motor goes in the housing

Not following on how you have the fuel lines arranged, can you give a better description?

Fuel flow out of the pump should fill a soda bottle in about 10 seconds, maybe less

Further thought: the pump can draw air thru the return line, if the tank level is low or the upper fuel filter is not filled
basically inside the HFCM the return is connected to the pump suction, there is a valve that should be closed at these temps, but may be leaking
you would need to cap both return fittings on the HFCM
@TooManyToys has a good video of the insides of the HFCM and how it works
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