High octane gas on ELANTRA

Discussion in 'Hyundai Elantra / Lantra' started by happy, Jan 15, 2007.

  1. happy

    Matt Whiting Guest

    This is an issue even if the tank is half full as water and most debris
    is heavier than gasoline and sinks to the bottom anyway.

    What does tank rusting have to do with running near empty?

    Yes, we've discused this hear before. I believe this is an OWT, but
    many still believe it. I don't know if hyundaitech has ever weighed in
    on this one though? How about it hyundaitech, does Hyundai have any
    official word on fuel pump cooling/life as a function of running the
    tank near empty?

    Matt
     
    Matt Whiting, Jan 18, 2007
    #21
  2. It has come up on other groups also. You are right about the OWT. Many
    have brought it up, but no one has actually given any evidence.
     
    Edwin Pawlowski, Jan 18, 2007
    #22
  3. happy

    PMDR Guest

    Assuming the tank is rusting inside, once the fuel level drops, more
    surface will be exposed to air, oxidize, and produce loose particles
    and debris.

    This happened to car in my extended family. It was always driven with
    less than a quarter tank of fuel to save weight and eventually the tank
    rusted from the inside out and sent debris through the fuel lines and
    clogged the fuel filter.
    I am pretty sure I've read that in more than one owners manual.
     
    PMDR, Jan 18, 2007
    #23
  4. happy

    Matt Whiting Guest

    With a modern closed system, you should not have air in the tank above
    the fuel, only fuel vapor.

    I've owned more than 10 cars in 32 years and have never seen this once
    in an official source. If you can post even one make/model and page
    number in the manual, I'd much appreciate it.

    Matt
     
    Matt Whiting, Jan 18, 2007
    #24
  5. happy

    Mike Marlow Guest

    Not sure I can go with this one Matt. Cars do not have a means of depleting
    air from the gas tank. They have the means to control the pressure in the
    tank relative to atmospheric pressure, but not the gases that make up that
    pressure. There is no way to remove the oxygen (even the levels typical of
    the air we breath) in a gas tank, thus oxidation is not only possible in a
    metal gas tank, but common.

    I'm not so sure though, how much of a problem oxidation from within the tank
    really is though. I believe more of the issues with contaminants inside the
    tank are from those contaminants being pumped into the tank at the gas
    station.
     
    Mike Marlow, Jan 18, 2007
    #25
  6. happy

    Matt Whiting Guest

    I can't find a reference at the moment, but I remember reading that one
    reason that there isn't an explosion concern with in-tank electric fuel
    pumps is that the tank has only liquid gasoline and gasoline vapor and
    not enough oxygen to support combustion or explosion. The explanation
    was that the charcoal canister traps excess gasoline vapor which is them
    drawn back into the tank as the fuel is depleted. Proper operation of
    this system requires the gas cap to be tightly in place hence the fact
    that most modern cars (I think OBD II and later) will light the MIL
    indicator.

    And, as I've mentioned previously, I run my cars down to 1/8 tank (until
    the light comes on) quite often and I've never had a tank rust out and
    have had only one electric fuel pump fail and that was after about
    150,000 miles so I don't think it was a failure due to overheating of
    the pump due to lack of gas in the tank as that would happen much sooner
    than 9 years and 150K miles.


    Matt
     
    Matt Whiting, Jan 19, 2007
    #26
  7. happy

    Mike Marlow Guest

    That would be interesting to read. If you find a link, post it or email it,
    will ya?

    I've never lost a fuel pump and I've driven my cars over 200K. I have lost
    a couple of tanks though, to rust. It appeared to be from the inside out,
    at the seams. These were all on GM's, but that's because except for the
    wife's Hyundai, GM's are pretty much all that have graced our garage. I do
    know of a lot of folks who have had tanks rot out on Fords as well. I don't
    admit to knowing people who own Chrysler products.
     
    Mike Marlow, Jan 19, 2007
    #27
  8. Moisture still gets into the tank due to condensation. Air has to be
    allowed into the tank as it drains and it brings moisture in with it.
     
    Brian Nystrom, Jan 19, 2007
    #28
  9. For that to be true, you'd have to have a vacuum in the tank. It simply
    doesn't work that way. As the fuel level in the tank falls, air is drawn
    in to replace it. There is no alternative.
     
    Brian Nystrom, Jan 19, 2007
    #29
  10. That's simply impossible. Yes, fuel vapor trapped in the carbon canister
    is drawn back into the tank along with outside air. The fuel is adsorbed
    by the carbon, then released as air is drawn through it and into the
    tank. There is no way to not have outside air entering the tank. To have
    a completely sealed system, you would have to pressurize and
    depressurize it as you add and subtract fuel from the tank. Fuel systems
    in cars don't work that way.
     
    Brian Nystrom, Jan 19, 2007
    #30
  11. happy

    Mike Marlow Guest

    Correct. If the vacuum existed as described, one would not be able to
    remove the gas cap, and all of our vehicles would share a common attribute
    with Jaguars - caved in gas tanks.
     
    Mike Marlow, Jan 19, 2007
    #31
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