Potential issue? Fuel pressure sound/vapour when opening fuel cap

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Ljc
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Drives: Polo Mk10 SE 95
Location: Kent

Potential issue? Fuel pressure sound/vapour when opening fuel cap

Post by Ljc »

Hi all,

Picked up my new polo SE 1.0tsi 95 on Saturday and went to refuel it last night. I’ll start by saying I’m not very mechanically minded! Upon opening the fuel cap it was almost as if there was a release of pressure and fuel vapour ( with accompanying ‘whooshing’ noise) which was considerably more noticeable than any other car I have had.

Now I’d expect some noise and vapour due to the vacuum/expansion levels changing when the fuel cap is opened, but has anyone here noticed it more on this car? Should I be concerned and contact the dealer?

Cheers
L
Andy Beats
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Re: Potential issue? Fuel pressure sound/vapour when opening fuel cap

Post by Andy Beats »

I've come across this on quite a few cars, but only when the fuel is really low.
You then often have to wait a few seconds or the pump will just continually click.
Was this the case?
Ljc
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Re: Potential issue? Fuel pressure sound/vapour when opening fuel cap

Post by Ljc »

Andy Beats wrote: Mon Dec 10, 2018 4:16 pm I've come across this on quite a few cars, but only when the fuel is really low.
You then often have to wait a few seconds or the pump will just continually click.
Was this the case?
Fuel level was between 1/4 and the red. It should be noted the car has only done 100miles and therefore the fuel the dealer put in would be the first proper running the fuel system has had(?), and this was the first time I have filled it up.

I had no issue with the pump clicking.
RUM4MO
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Re: Potential issue? Fuel pressure sound/vapour when opening fuel cap

Post by RUM4MO »

Are you sure that what you heard was a pressure release and not a slight vacuum release, when the engine is running, it, under certain conditions operates the EVAP solenoid and that will allow the induction side of the engine to purge the carbon canister that traps petrol fumes, by applying a slightly lower than ambient pressure to that canister it will result in the pressure in the tank being held slightly below ambient air pressure.
monkeyhanger
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Re: Potential issue? Fuel pressure sound/vapour when opening fuel cap

Post by monkeyhanger »

It's always a sucking/low pressure noise for me when filling up. Just been stood 3ft from the best car I've ever seen - I'm in Strasbourg with work and been looking at the Bugatti Chiron that's encased in a glass box (the Bugatti family are based in Molsheim, not far away, where I'm auditing a Chemical company tomorrow)
Adam_013
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Re: Potential issue? Fuel pressure sound/vapour when opening fuel cap

Post by Adam_013 »

Yeah, I get it too most times when filling up. I'd say nothing to worry about.

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Ljc
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Re: Potential issue? Fuel pressure sound/vapour when opening fuel cap

Post by Ljc »

Thanks all.

I’ll keep an eye on it just in case!
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