Fuel Petrol Fill Up

[Tigerclaw]

Hay Peeps im kinda new here so this may have been answered but i couldnt find it using search.

i've had my civic since november last year, and have noticed every now and again when i go to fill up the space ship that a high amount off pressure has built up in the petrol tank.

let me explaine

i run the car till i have about 20ish miles left in the tank which is just about as the low fuel indicator comes on (going by the reader in the civic) i pop into my local shell garage and stick some juice in.

i pop the petrol door open and as soon as i undo the petrol cap i can hear either air escaping or more likly air being pulled into the petrol tank.

im not to worried cos the car seems to run fine and i havent had any problems yet apart from some little ******* kicking my driver side door.

just wondering if i should get it checked out or just just lay it down to running the petrol down to low.

[Dalboy]

Happens on mine as well and other cars I have owned so don't worry

[Dimplyred]

It's the car breathing a sigh of relief, that it made it to the petrol station.

[Selwoc]

Can't say that I've noticed it on mine, does this apply to diesel and petrol tanks?

[civicfan]

Originally Posted by Tigerclaw

Hay Peeps im kinda new here so this may have been answered but i couldnt find it using search.

i've had my civic since november last year, and have noticed every now and again when i go to fill up the space ship that a high amount off pressure has built up in the petrol tank.

let me explaine

i run the car till i have about 20ish miles left in the tank which is just about as the low fuel indicator comes on (going by the reader in the civic) i pop into my local shell garage and stick some juice in.

i pop the petrol door open and as soon as i undo the petrol cap i can hear either air escaping or more likly air being pulled into the petrol tank.

im not to worried cos the car seems to run fine and i havent had any problems yet apart from some little ******* kicking my driver side door.

just wondering if i should get it checked out or just just lay it down to running the petrol down to low.

I guess you're right in thinking it's air being pulled into the tank, if it's more than just barely noticeable, it is a serious fault - in this case you should go to the dealer to have your tank de-pressurizing repaired (preferably come with an empty-ish tank so he can hear the noise). It is important, because if you fill up at a cool day, park the car, and next day (in summer!) it's hot, your fuel tank may burst - air/fuel vapor is compressible but liquid fuel is not

[Munro]

It does it on mine as well - a lot more than on any other car I have had. It doesn't seem to cause any problems though.

[Steeph]

Originally Posted by Tigerclaw

i pop the petrol door open and as soon as i undo the petrol cap i can hear either air escaping or more likly air being pulled into the petrol tank.

I think this is normal, just caused by pumping fuel out of the tank. Probably there is a seal somewhere that only opens to let air in if the pressure gets below a certain threshold. This way there is always a underpressure in the tank compared to the outside pressure so petrol fumes can not escape and cause dangerous situtations. It would also compensate for any fuel/air-expansion if the car would be parked in the sun in the summer.

[RFY]

Yeah mine does it too and its the 1st car i have had that makes that noise. But like other people have said its not caused me any problems so far, so im not too bothered about it.

[robbo51]

Its a pressurised system. Quite normal I believe

[Blib]

I've come across it on several cars that I've owned, including this one. I would think nothing of it.

[jazzman]

Originally Posted by Tigerclaw

Hay Peeps im kinda new here so this may have been answered but i couldnt find it using search.

i've had my civic since november last year, and have noticed every now and again when i go to fill up the space ship that a high amount off pressure has built up in the petrol tank.

let me explaine

i run the car till i have about 20ish miles left in the tank which is just about as the low fuel indicator comes on (going by the reader in the civic) i pop into my local shell garage and stick some juice in.

i pop the petrol door open and as soon as i undo the petrol cap i can hear either air escaping or more likly air being pulled into the petrol tank.

im not to worried cos the car seems to run fine and i havent had any problems yet apart from some little ******* kicking my driver side door.

just wondering if i should get it checked out or just just lay it down to running the petrol down to low.

Quite normal on all cars as the tank is pressurised but more noticeable when you let your fuel run down to very naughty levels.

[FWH]

Normal.

My Civic does it as have all or at least most of my other cars.

[garytheobald]

does it on my rx8 OFTEN as its always getting refuelled but only until 29th when it goes and my ctr arrives on 1st march then isle of man mountain road 1 week later

[vlmxs]

Originally Posted by Dimplyred

It's the car breathing a sigh of relief, that it made it to the petrol station.

LOL

[Palindrome]

Nothing to worry about,as the tank empties this creates a vacuum,due to new emissions/enviormental laws fuel vapour this is no longer allowed to escape to the atmosphere but is caught in a carbon canister thus creating a sealed system.
In extreme cases where this system fail it can cause the tank to collapse but very rare.

[Tigerclaw]

well thats all nice to hear lol

and as to the car breathing a sign of relief lol

it probaly is but i always seem to make it home from work and i love the car for it.

have noticed that as soon as i see that i only have 60 miles left in the tank i seem to drive a lot more "normal" lol.

i blame the fantastic sounding engine at the higher end of the rev range but hay

[civicfan]

Originally Posted by Palindrome

Nothing to worry about,as the tank empties this creates a vacuum,due to new emissions/enviormental laws fuel vapour this is no longer allowed to escape to the atmosphere but is caught in a carbon canister thus creating a sealed system.
In extreme cases where this system fail it can cause the tank to collapse but very rare.

Then perhaps what I have written previously (about de-pressurizing) is not valid any more with today's cars - but then again, why does my Civic _not_ make any noise when opening the fill port?

[angie4m]

Originally Posted by civicfan

Then perhaps what I have written previously (about de-pressurizing) is not valid any more with today's cars - but then again, why does my Civic _not_ make any noise when opening the fill port?

You probably just haven't noticed. Its not the loudest noise in the world.

[Dalboy]

Originally Posted by angie4m

You probably just haven't noticed. Its not the loudest noise in the world.

More of a wisper

[civicfan]

Originally Posted by angie4m

You probably just haven't noticed. Its not the loudest noise in the world.

OK maybe... I'm generally quite sensitive to strange noises about the car, but filling is not driving I'll pay attention with my next fill (in approx. 3 days) and then post my observations. Still hard to believe that modern cars don't have de-pressurizing any more - is the fuel tank of some "elastomere" plastic?