High octane gas on ELANTRA

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

Reply to
Matt Whiting
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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.

Reply to
Edwin Pawlowski

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.

Reply to
PMDR

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

Reply to
Matt Whiting

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.

Reply to
Mike Marlow

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

Reply to
Matt Whiting

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.

Reply to
Mike Marlow

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.

Reply to
Brian Nystrom

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.

Reply to
Brian Nystrom

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.

Reply to
Brian Nystrom

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.

Reply to
Mike Marlow

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