Gush of air when opening fuel cap

Went to the petrol station today in my 92 fashion line, and as I opened the fuel cap a gush of air came out and obviously the smell of petrol came with it, does anyone know why it's doing this?


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Roughly how much petrol did you have in your tank?
I'm mean I'm guessing you had to refuel for a reason.

My two golf's, the Mk1 and Mk6 do that all the time no matter have much fuel is in the tank.

As far as I'm concerned that tells me I've got a good strong seal on the cap. 👍

But maybe someone knows better! 🤔😉

My fuel level was just out of the red I never let them get into the red, my other mk1s don't do it so I'd just like to know whether it's a problem or not


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My money is still on a good tight seal but let's wait for the real experts at this club! 👍

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heres a tidbit i found a while bacvk, I forget who it was who posted it:

"There are two cap types, vented and non vented, GTIs must have a non vented one fitted.
You will find "Ohne blau Lüftung" stamped on the metal part."

so that would suggest carb engines should have a vented cap on it, if yours is not that could be why

Thats strange as I bought a vented cap for my swallow and it still made a gushing sound when I opened it the other day after a drive……. (it's only drive!)


All my mk1's have done it.

other thing is i cant find any evidence in etka that gti caps are actually different from carb ones

possibly the tank vents are blocked/kinked somewhere? you have some pipes up to the gravity valve in the wheel well and a long thin pipe that pokes out behind the tank somewhere

My fuel level was just out of the red I never let them get into the red, my other mk1s don't do it so I'd just like to know whether it's a problem or not


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Hi i had similar experience in yuppie last summer, before i could investigate further, i blew a fuse to fuel pumps… after that i checked filters and antigravity valve sucked and blew on small pipes😘 all seemed to be working, changed fuel cap to vented type as i was concerned pumps vacuum the tank,causing fuse to blow with strain. Not happened to same whoosh since. But i do open cap before and after run out.

I have had this issue on all my Cars VW Diesel as well as  Gassers.

84.5 Cabbies and up, have an in-tank pump.
If the In-tank interconnected is weak, or holed then 45 psi can fill the tank.

If the fuel regulator (DIGI) is Wonky, or your running down the road, Fuel is returned to the Tank under Pressure.

If you have a good working system then up to 29 psi can stay in your tank with a vented or non vented cap, and it depends on what the cap is rated for.

On a hot day Fuel will expand as in GAS…..
On cold DAYs it will contract

So what I have noticed is that on Cold days it vents less
than on hot running down the road days.  

The Emission Nazis over here Tests the CAPS for holding pressure as a VENTING cap screws the environment adding to GLOBAL CLIMATE CHANGE, Increasing the CARBON FOOTPRINT Melting the POLES,
"Funny I haven't seen any photos of Polish people Melting or getting smaller" causing the Polar Bears and Muskox to look for towns with large Freezers……

So I would Say, NORMAL, as I know it.

I've always had the 'air gasp' when I take the cap off. 15 years and counting.

If the car is not suffering any running issues due to fuel then does it really matter whether it makes a gasping sound or not?   

I for one am not bothered in the slightest!  

it may be the vented caps were made NLA many, many years back if they ever existed. My MK2 has never done this, I expect the newer tank was designed not to either that or the fact its made of plastic reduces the affects

Mine says ohne kohler loftung no idea what type of cap it is


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Mine did this when first got it last summer. I got a new Hella cap and it stopped doing it.

Your cap is unvented - that's what the German means.

ohne kohler comes out as 'without coal' so I would assume that means for cars without the carbon canister system

No idea what that means mate haha


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in certain market rather than venting to atmosphere the tanks vent through a canister containing charcoal back to the inlet manifold, better for the environment

in the UK market we didnt get that till the mk3 golf

Ahh right fair doos is it normal for that air to come out then or is there a problem?


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