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Yet another problem with the s3

Discussion in 'A3/S3 Forum (8L Chassis)' started by Goubo1, Jan 14, 2012.

  1. Goubo1
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    Goubo1 Member

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    Tonight I replaced the the small vacuum hose that had spilt and the the inlet pcv breather pipe.I took the car a rather spirited drive and it seems a bit more responsive on acceleration.on the way home I pulled in to the petrol station for some fuel I open the filler cap and lots of pressurised air and petrol came gushing out can any one tell me or give me a clue to what's causing this ? Also if I remove the oil cap air gushes out as well
    Last edited: Jan 14, 2012
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  2. Goubo1
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    Goubo1 Member

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    Also when the car is switched off I can open the filler cap and release the pressure with little to no fuel coming out but if I leave the cap of and start the engine fuel gushes out.
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  3. Alex C
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    Alex C Active Member

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    i would guess that if air rushes out when you take the oil cap off then its not breathing properly, have you checked for blockages in the PVC system?

    not sure how or if that would affect your fuel system though
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  4. Goubo1
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    Goubo1 Member

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    Am I right in thinking that if it was not breathing properly it would not be running very? As its running better than it was before I replaced the the hoses
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  5. s3dave
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    s3dave TFSI Hybrid

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    I would check the pipes around the charcoal canister next to the screen washer bottle..
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  6. Goubo1
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    Goubo1 Member

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    For blockages or being disconnected dave ?
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  7. s3dave
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    s3dave TFSI Hybrid

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    I think it is suppose to vent there so maybe blocked?
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  8. Goubo1
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    Goubo1 Member

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    There was on plastic hose that had split but got replaces with a silicone hose and made no difference.my charcoal canister is making a rather loud clicking noise,do you happen to know what hose is the vent hose dave ?
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  9. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    Sounds like what ever you have done to repair the pipes you have either missed off a check valve somewhere or piped it up wrong... would appear both your engine and fuel tank is seeing boost pressure

    <tuffty/>
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  10. s3dave
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    s3dave TFSI Hybrid

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    It goes to the bottom of the canister and out through the wing
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  11. Goubo1
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    Goubo1 Member

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    It was just the 2 braided hoses that lead under the manifold that got replaced dv to n249 hose and the plastic pipe I found yesterday from the charcoal canister.they got replaced like for like 1 at a time so I could not get them mixed up

    I opened up the filler tank and started up the engine and it gushed out on idle does this rule out the possibility of it being boost related as I was not on boost when this occurred ??
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  12. Goubo1
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    Goubo1 Member

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    Cheers dave I will check that out
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  13. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    There are a couple of one way valves in use with the charcoal canister... one vac pipe comes from the top of the throttle body and the other from the TIP...

    Check the pipe work on these... if the tank is seeing boost then its more likely to be the one on the throttle body... there should be a one way valve on the pipe just before it goes into the hard pipe that runs across the back of the engine bay...

    <tuffty/>
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  14. Goubo1
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    Goubo1 Member

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    Tuffty would it be possible for you to show me this pipe on a picture if you could ?
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  15. Goubo1
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    Goubo1 Member

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    Well the problem turned out to be a blocked breather
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  16. Alex C
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    Alex C Active Member

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    woop woop :yahoo:
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