overflow

[honda]

When I fill up the gas all the way, often the next day it will have overflowed, coming out of the gas cap, and will be dripping from the overflow. Does anyone know why this happens?

[kaltenacht]

What do you mean by fill all the way up? To "F" on the gauge or over "F". If you fill up over "F" then there is your answer. Dont over fill!

[honda]

I fill it up until the gas pump turns off, automatically. Last time, I filled it up, drove it a while so the gauge was at 0.9 full, and it still overflowed the next day.

[Blkblurr]

Are you filling up when it's cool outside and later on it gets hot? That will cause the gas to expand and overflow.

[smufguy]

once the gas tank is tooo full, it might overflow, but seems like ur just toooo full. Usually it never happens since once u start driving it will burn some gas, But of course when the temperature and pressure builds up in the gas tank, u might overflow. But it never happened to me, so this is something unique. but never overfill ur tank.

[honda]

Filling up when it's cool/and then a warm day after it's filled causing it to overflow: that's what I had been thinking. But this last time I filled at 5:00 pm (still warm), and next morning, it had overflowed (by noon). I don't think there was that much of a temperature change between the two times.

AND, what about when it's clearly below the "Full" like after I recently filled it up and drove it (so that it was at 0.9 full), and then the next day it had overflowed? If it's not even at the Full mark, then it definitely should not be overflowing, right?

[kw_da]

The fuel is cold when going into your tank - it probably comes from an underground tank that is cold. So the fuel could expand as it warms up in your tank

However, I only have this problem if I overfill my tank & park on hill.

Is the fuel coming out of the fill nozzle, or lower from the pipe? I remember there was a recall on my Honda where the fuel fill pipe was corroding - this could cause fuel to spill out from the pipe.

David

[bobafett]

a guess:

might be that the charcoal cannister evaporation thing is plugged. normally excess gas 'fumes' normally get collected in the charcoal canister. if you are not able to vent gas into this, since your gas cap is sealed, and there should be no other vents in the system, it will build up enough pressure to leak.

try pulling off your gas cap every couple of hours after filling up to relieve pressure. it seems crazy that you would have liquid overflow and not jut gas fumes escaping

[A20A1]

I never fill up my tank all the way... why carry around extra fuel/weight if you don't need it. Though if you know gas prices will raise the next day... then its better to stock up.

Your exhaust pipe or muffler isn't touching... or installed too close to the fuel tank or without the heat shield is it?

[honda]

it's actually coming out of the top, where you fill. I can't say exactly where at the top, but i've seen gas pouring out of the the little door that covers where you add fuel. i have one of those older gas caps that is all metal, I don't know if that makes a difference.

charcoal canister thing? what is that? can I replace it myself? and what does the heat shield look like (can I see it)?

I looked at the fuel fill pipe. from what I can see it looks allright.

if i do need some repairs done, who does this kind of thing?

[honda]

i now know what the charcoal canister thing does. where is that, and does anyone know where the heat shield is located?

[bobafett]

the charcoal cannister is in the engine bay, its a big black plastic cannister. the heat sheild would be above your muffler on the back of the car, and underneath the gas tank.

[azazel_18_2]

Hey, replace the gas cap. It should seal to where NOTHING will leak out.

[Oldblueaccord]

uh its vented or else your gas tank will burst from to much pressure

There allotta venting tubes on gas tanks for emissions and other wise. It sounds like something is wrong there. It is not normal for gas to come out the cap EVER EVER unless you grossly over fill it which it sounds like you have not.


wp

[A18A]

all i can say is dont park ur car outside or in a hot place, u neva know, u might come back and find your car on fire

[smufguy]

all i can say is dont park ur car outside or in a hot place, u neva know, u might come back and find your car on fire

lol that was comforting

[azazel_18_2]

I know the tank is vented but he said it is leaking from where you put gas in it not at the tank. Try the cap.

[bobafett]

i was under the impression that part of the emissions TESTING even tests that your gas cap is sealed!

my understanding of the system is the pressure gets purged into the charcoal cannister, which eventually ends up back in the gas tank... but the pressure was relieved to the charcoal cannister. i havent read up on this system, but that was my general assumption...

[honda]

well yesterday i filled it, let it fill up till it turned off automatically. But when it turned off automatically it had overflowed (I haven't seen it do that before)! So it's possible it's been overfilled before, and the automatic turn off has not been turning off soon enough. I still want to consider the other things people mentioned though. I don't think I'll be able to see the heat shield but the charcoal canister maybe.

[A18A]

try going to another gas station then, there pumps are prolly fudged up

[A18A]

i know this is a old thread but i was reading threads on trademe and this is what i found:

do you know at night you will get more fuel
on a cold night then on a hot summer day. Becouse petrol-diesel expands with heat, i only know this becouse i knew a tanker driver who only did fuel delivery he sayd they are only to fill 3/4 as it expands that mutch in the tanker when sun gets on to it. he had once to pump some off again fast as it started overflowing Filled it 5am on crisp summer morning and 4h later the thing overflowed.

very interesting, lets buy petrol at night