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Fuel pressure test

1animal1 Sep 5, 2008

  1. 1animal1

    1animal1 The Clar!! it mouves!!!

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    Owing to the several cases that have surfaced with fuel pump problems, i had a chat with a mechanic mate who is going to pressure test for me.....

    firstly, where is the fuel pressure rail under the bonnet of the S3

    secondly, what sort of readings should we be getting to rule this in/out

    This is in the hope that this could be giving me the lumpy boost
     
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  3. HTC

    HTC Registered User

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    The correct way to test is via fuel delivery rate and system pressure as follows.

    Fuel Delivery Rate:

    * Remove number 28 fuse.
    * Make up wire that has a switch in it.
    * Connect one end of the wire to the contact at the fuse box where you removed the fuse.
    * Connect the other end to the battery +12v terminal (don't switch on yet)
    * Remove the fuel delivery pipe and put it into a measuring jug. Pipe No.2 in the diagram.
    [​IMG]
    * Attach a voltmeter across the terminals of the battery.
    * Turn on the switch in the lead to run the pump. Run it for 15 seconds and remember the voltage reading whilst its running.
    * Compare the amount of fuel delivered with this diagram. It's a graph of minimum delivery Vs voltage. Voltage can be a couple of volts lower than when the car is running. This is okay.
    [​IMG]


    System Pressure and holding test:

    * Connect a pressure gauge with cut off valve inline within the fuel delivery pipe
    [​IMG]
    * Run the engine. Pressure gauge should read 2.5bar
    * Disconnet the vacuum pipe from the fuel pressure regulator. The pressure should rise to 3bar.
    * Turn engine off and watch the gauge. After 10 minutes the gauge should still read a mimimum of 1.5bar.

    To locate the injector rail. Remove the main engine cover. Look at the inlet manifold. On top of the runners you'll see the injectors. The metal pipe connecting them is the rail. On the right hand side at the end of it is the fuel pressure regulator.
     
  4. 1animal1

    1animal1 The Clar!! it mouves!!!

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    HTC you are a legend......will post up progress once ive done.... hate this trial and error s**t
     
  5. mephisto

    mephisto Registered User

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    Just reviving this as I have a starting issue and it is spluttering under accelerating. Takes a good 10secs to start from cold but seems once I have good fuel pressure it starts fine. Leave it a few hours and its back to taking ages to start.wondering if the regulator is playing up here.
     
  6. mephisto

    mephisto Registered User

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    HAs this forum died a death, i rarely see a reply lately let alone much talk?
     
  7. Tj 0785

    Tj 0785 Registered User Bronze Supporter Silver Supporter VCDS Map User

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    Seems to have died down as with all forums nowadays, just the same few now that seem to be around
     
  8. mephisto

    mephisto Registered User

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    Mm a shame, on top of that alot of the images disappearing due to photobucket etc expiring the images the bstards. I might start archiving off what's left here!

    I guess that's also reflecting how many less are on the roads now too, i see many areas on Facebook now where people are ripping through 8Ls breaking them.
     
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  9. Tj 0785

    Tj 0785 Registered User Bronze Supporter Silver Supporter VCDS Map User

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    yeah Facebook not really helpful like a forum people just tend to take the pi55 out of people asking for help
     
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  10. Sandra

    Sandra Administrator Staff Member Administrator Platinum Supporter Audi Main Dealer

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    This section has quiet spells, the forum as a whole is busy
     
    Tj 0785 likes this.
  11. Tj 0785

    Tj 0785 Registered User Bronze Supporter Silver Supporter VCDS Map User

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    As the cars get cheaper younger drivers can afford them and they are more likely to be Facebook than a forum unfortunately I wouldn’t think there is many members under 25 on here
     
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  13. Sandra

    Sandra Administrator Staff Member Administrator Platinum Supporter Audi Main Dealer

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    Good amount of Under 25’s on the forum, Cars are easier to get these days and the youngsters like the best. :)
     
  14. Brad1011

    Brad1011 Registered User

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    Yeah some sarccy divs on there but I got a question resolved on there the other day which could of had some dipstick replies I did ask on here first...


    Sent from my iPhone using Tapatalk
     
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  15. mephisto

    mephisto Registered User

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    So true, Facebook and 'Like' has evolved into a breeding ground for 'who can outsmart the original poster the most with an amazing 'witty' retort'

    Its mind numbingly boring and i agree really doesn't help in most cases because questions are greeted by 'captain know-itall obvs' . Which can then descend into a slanging match. Not a match ever for Forums like here, stickies build threads etc which is a real shame. Hope it comes back sometime.
     
  16. HTC

    HTC Registered User

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    Sorry, those pictures are missing. Photobucket stopped allowing shares to forums a while back. I don't even remember my login details :-(

    I like forums more than Facebook and Twitter etc. YouTube definitely has its place for good info.

    I still have my 8L A3 stored, but I haven't seen it for years (I left the UK 10 years ago).

    When I return to the UK for my next visit, it will be up for sale super cheap. No idea when that will happen due to covid.

    Watch this space.

    Hope you manage to fix your issue.
     

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