That’s probably because you can’t compress a liquid (fuel) but you can compress a gas (Fuel vapour), so the emptier the tank gets the more spare there is for vapour and the more comes out when you open the filler cap.
The breather is quite a large bore metal pipe (~3mm) except for a black plastic restrictor pushed on the end which takes it down to around 0.5mm. The breather pipe should end just below the level of the flange joint in the tank along the front of the tank. It may have been extended with a length of rubber tube as well. But, if it’s blocked it will be where the restrictor is. I have seen some tanks without the restrictor but it can let a fair amount of fuel out. Jim From: Mark Miles Sent: Thursday, June 21, 2012 12:07 AM To: quantumowners@googlegroups.com Subject: Re: [Quantum Owners] tank pressure Mine also does this, strangely it gets worse the lower the fuel level gets. Mark Miles Manager roebuck 8 Market Place Wokingham Berkshire RG40 1AL 07935 068776 -------------------------------------------------------------------------------- From: Susan and Martin Scott <susanandmar...@corringham99.free-online.co.uk> To: quantumowners@googlegroups.com Sent: Wednesday, 20 June 2012, 21:57 Subject: Re: [Quantum Owners] tank pressure Do you have a return line from the engine to the tank? Warm fuel going back can give positive pressure. ----- Original Message ----- From: "jin" <jinmys...@btinternet.com> To: "Quantum Owners Group" <quantumowners@googlegroups.com> Sent: Wednesday, June 20, 2012 9:44 PM Subject: [Quantum Owners] tank pressure i seem to be getting positive pressure in the petrol tank at the moment, i assume it means my breather is blocked but i cant explain the positive pressure? you would assume its negative as its constantly being emptied (quite quickly too) but there is a definite blow as you remove the cap, so im bemused as to where its coming from, also is there an easy way round this without removing the tank? like a vented cap or T into the fuel line? cheers -- You received this message because you are subscribed to the Google Groups "Quantum Owners Group" group. To post to this group, send email to quantumowners@googlegroups.com To unsubscribe from this group, send email to quantumowners-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/quantumowners?hl=en IMPORTANT NOTE: All information presented herewith is provided on an "As Is" basis, without warranty or the implication thereof. Neither the Quantum Owners Club nor the individuals associated with the Quantum Owners Club or in the preparation of the above information shall have any liability to any person or entity with respect to liability, loss, or damage caused or alleged to be caused directly or indirectly by the instructions contained within this or related message(s). ----- No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1424 / Virus Database: 2433/5081 - Release Date: 06/20/12 -- You received this message because you are subscribed to the Google Groups "Quantum Owners Group" group. 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