Presure release when opening fuel cap

Comuscomp · Feb 23rd, 2015, 12:47

I have just experienced something with my V50 2.0d MY2008, which hasn't happened before.

I went to fill up with diesel, when I undid the fuel cap there was a whoosh of pressurised air from the tank, the engine wasn't running, is this something to worry about?

I have had the car a few years now and have never had this happen before, could this be a sign of something starting to go wrong?

Tony500 · Feb 23rd, 2015, 14:18

Its normal to happen....

Welton · Feb 23rd, 2015, 14:55

Mine does it a lot, more after just a short run to the garage. Sometimes it's a huge draw of air. The tank runs a slight negative pressure so that the fuel 'fumes' can be recovered to a charcoal canister in the engine bay and neutralised.

woody6046 · Feb 23rd, 2015, 22:39

this used to happen when the air hole in the fuel cap was blocked , just put a straight pin or piece of wire into it to clear it and it should do the trick .

Feb 23rd, 2015, 12:47	#1
Comuscomp Junior Member Last Online: Sep 11th, 2022 15:55 Join Date: Aug 2011 Location: Chertsey	Presure release when opening fuel cap I have just experienced something with my V50 2.0d MY2008, which hasn't happened before. I went to fill up with diesel, when I undid the fuel cap there was a whoosh of pressurised air from the tank, the engine wasn't running, is this something to worry about? I have had the car a few years now and have never had this happen before, could this be a sign of something starting to go wrong?

Feb 23rd, 2015, 14:18	#2
Tony500 Master Member Last Online: Jan 7th, 2024 14:02 Join Date: May 2014 Location: Glasgow	Its normal to happen.... __________________ 2009 V70 R-Design 2.0D SE Sport 2007 XC90 D5 SE Lux 2006 XC90 V8 Executive

Feb 23rd, 2015, 14:55	#3
Welton Premier Member Last Online: Sep 14th, 2021 17:03 Join Date: Feb 2009 Location: Market Harborough	Mine does it a lot, more after just a short run to the garage. Sometimes it's a huge draw of air. The tank runs a slight negative pressure so that the fuel 'fumes' can be recovered to a charcoal canister in the engine bay and neutralised. __________________ 2005 S40 T5 SE - Manual. Bilstein B4's. (For Sale) 2010 Citroen C4 1.6 HDi (bizarre Gearbox model). 2010 Renault Twingo (refreshingly simple) 2018 Infiniti Q30 1.6T Business Executive (what's this button do?)

Feb 23rd, 2015, 22:39	#4
woody6046 woody Last Online: Mar 1st, 2015 23:07 Join Date: Aug 2012 Location: poole	this used to happen when the air hole in the fuel cap was blocked , just put a straight pin or piece of wire into it to clear it and it should do the trick .

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