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
    brford and GlassTop09 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!

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