The problem of refueling !!

Discussion in '2005+ Mustang GT 4.6L Tech' started by datmbn, Jan 15, 2020.

  1. datmbn

    datmbn forum member

    I find it rather strange that no one seems to have investigated the causes of the problem.
    Some cars work well, so the problem must be solvable !!
    I've looked at the problem, and found both cause and solution (I think)
    The biggest problem with finding a solution is that the problem consists of 2 different basic problems with several
    secondary problems.
    Some cars suffer from problem 1 others from problem 2, and some really hopeless ones suffer from both.
    1: Ventilation problem.
    In order for the fuel to enter the tank, the air that is there must come out.
    The venting starts on the right side of the tank, here there is some kind of puff vent box inside the tank, as early cars
    had problems with <2006, then it is tank change that applies, which is usually done as a service measure / goodwill.
    When the air leaves the tank it then passes through a 16 mm hose back past the rear axle, arrives at a three way intersection,
    (from tank-to vent-to intake manifold on the engine via evap valve) then it passes through a vent-valve, a carbon filter,
    a dust filter, and a hose stump that opens just behind the rear axle.
    As we can see, there are several "probable" points that can cause the air to go slow or completely tight.
    A. The hose from the tank goes quite close to the exhaust system as it passes over the rear axle, so it may
    has melted/softened to become slow/tight (may have also collected condensation water at some low point)
    Solution: change hose or blow clean.
    B. The three-way intersection may have caught debris (not likely since it is filters in all directions, but worth checking out)
    Solution: Blow clean
    C. The vent valve does not open properly, it must be fully open when the car is switched off
    Solution: Replace valve or lubricate and shake, coax on it.
    D. The carbon filter is more or less tight so that the air passes too slowly
    Solution: New filter, or replace the filter with a hose stump (if replacing the filter with a hose stump
    you can sometimes feel a small gasoline smell during refueling)
    E. The dust filter may be clogd.
    Solution: Blow the filter clean or buy new
    F. The hose stump can be clogd (quite common for spiders to make nest in the mouth)
    Solution: Blow the hose clean.
    As we can see, there are at least 6 different reasons why the venting does not work, and thus at least 6 different solutions.
    Some cars may also have a combination of these problems, which is why it is good to check them all when you start to tear into this.

    2: Problem with "air lock" in the filler pipe
    In order for the fuel to enter the tank, free passage is also required, nothing must be in the way, not even air
    The filler pipe starts in the filler cap goes downwards under a longitudinal beam, and then a little upwards over the rear axle, then
    angle down and drop into the tank at about 3/4 of the maximum level.
    Seen from the side, the filling tube more or less forms a lying S, which is ok as long as the liquid surface in the tank is lower than
    If you start refueling with an "empty" tank, the fuel will push the air that is in the pipe in front of it into the tank and fill the "whole"
    pipe with fuel, and as long as you do not stop or otherwise get air in, full flow will be maintained.
    If you start refueling with fuel level above the inlet of the tank, the fuel will try to push the air in the pipe in front
    down in the tank, but fail, because the fuel in the tank is in the way, the air will instead be compressed to some extent and
    leave little or no passage.
    This condition of "air lock" can also occur during refueling if the gas station has a lot of bubbles in the fuel.
    (remedy something by having the nozzle between 11 and 1 a klock , and far out)
    In order to remedy this problem, one must try to "stretch" the S as far as possible so that any air can expel the back way
    via the filling tube.
    The first step will then be to loosen / extend the pipe bracket before the tank, and to cut 5-10 cm of the hose, which then
    happens is that you lower the highest part of the filling tube, and that you pull forward the bottom part of the tube that will
    come closer to the beam / higher up.
    I think this measure is in most cases enough.

    The second step (if nothing else works) saw holes in the beam at the appropriate place, and weld in the appropriate pipe as reinforcement.
    You can then thread the filling tube that way, thereby creating down sloap all the way (this is what it looks like from 2008 onwards)
    Hope this clarified something
    My car suffered from problem 1D and I solved it with a hose stump, works perfectly now.
    regards Mats
    XJCasper, crjackson, Kev555 and 2 others like this.
  2. GlassTop09

    GlassTop09 Member

    Good stuff to know as these cars are getting long in the years where EVAP issues will or have already starting slowly occurring....just recently had to resolve an issue happening on my car where a part of the EVAP system was failing causing issues (not the refueling issue as my car is a '09 which has the filler neck issue you've mentioned resolved by Ford & the symptoms I was TS'ing didn't include refueling issues w\ the gas tank at the time) even though the PCM was showing the EVAP system passing....but certain areas of the EVAP system failing can indeed cause the refueling issues you've so systematically laid out here.

    Kudos for posting!

    crjackson likes this.
  3. Kev555

    Kev555 Member

    Ive cured mine by Disabled the anti-spill? float in the tank mouth by jamming it open with a bit of copper brake line where the pipe goes on which causes a restriction to the fuel going into the tank. All Credit for this must go to a friend of mine Daryl as he discovered disabling the float which cured his. I welded a 10mm PCL air line fitting to my fill pipe at the point where the air gets trapped. I then ran a 10mm fuel line up though the bung in the floor at that point and took it out through the boot and inner rear fender to the fuel cap area as this was all rising rather than following the fill pipe which could have caused an air lock in the 10mm fuel line as well. I fitted a small turn valve in the fuel cap area if I need to operate the air bleeder pipe. So far I haven't needed it as there must be enough expansion in the pipe itself to cure the airlock, I cant say which mod has helped the most as I done both at the same time but no problems filling now. I realise some of the mods ive done may be illegal in the US
    dark steed likes this.
  4. crjackson

    crjackson Member

    Everything you do to, or with, your Mustang is illegal these days.

    Fk’em do what you need to do….

    Attaboy to OP for his investigation and post!
    Last edited: May 2, 2022
    golkhl likes this.
  5. bambam 06

    bambam 06 Member

    Can you show a picture of this repair?
    Kev555 likes this.
  6. Laga

    Laga Senior Member

    CDE735C8-BE94-42DB-920C-8C077F4E1226.jpeg This has worked fine for 17 years.
  7. Kev555

    Kev555 Member

    Lol tried that too didnt work on any occasion
    XJCasper and Aerofinz like this.
  8. Kev555

    Kev555 Member

    Yes i will post pictures in a while i forgot to photograph the vent on the fill pipe before i refitted it. I might have it on the lift for a diff oil change this week or next, i will do it then.
  9. Aerofinz

    Aerofinz Member

    Last edited: May 4, 2022
  10. Laga

    Laga Senior Member

    Those are not new. These pumps have been around for decades. This is one of the reasons that there is a myth about damaging the carbon canister in the EVAP system by over filling. When they were first used nationally back in the 1990’s, they could malfunction and cause gas to be pumped under pressure into the tank. This did harm the early EVAP systems. They could also fail to shut off and continue to pump gas into the return part of the pump hose. Causing customers to pump 30 gallons into a 20 gallon tank, for example. That’s why they were discontinued nationally. 542507E6-F6A3-4835-B866-5868E8FB9624.jpeg
    Kev555 likes this.
  11. Aerofinz

    Aerofinz Member

    Last edited: May 4, 2022
  12. Kev555

    Kev555 Member

    IMG_20220620_165437395.jpg IMG_20220620_165228353.jpg IMG_20220620_165155758.jpg IMG_20220620_173031493.jpg IMG_20220620_165437395.jpg IMG_20220620_165228353.jpg IMG_20220620_165155758.jpg IMG_20220620_173031493.jpg IMG_20220620_165437395.jpg IMG_20220620_165228353.jpg IMG_20220620_165155758.jpg IMG_20220620_173031493.jpg
    As promised pictures of the mod thats working well the little valve at the fuel cap I have never found I needed it yet as 9 out of ten fills goes to full tank without any hassle. I dont let the tank go more than half empty ATM due to mental hurt filling it from empty LOL. Pipe goes up through bung in boot floor at that point directly above and carefully routed through the boot rising all the time and out through the inner mudguard and finishes at the filling cap
    Last edited: Jul 3, 2022
    Jean Margaret likes this.
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