Mk1 Golf - Fuel starvation on right hand bends.Analysis and conclusion

Discussion in 'Engines' started by vw_singh, Jun 30, 2009.

  1. vw_singh Events Team Paid Member

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    Note: Images taken from other forums.

    As many of you mk1 owners have already suffered or seen, mk1 golf tend to suffer from detrimental fuel starvation on tight long right hand bends. The general consensus has been that the mk1 tank isnt up to the job due to the lack of a proper lift pump and a poorly designed tank. But the interesting thing is that this problem doesnt seem to be consistent across all mk1s. The fact is that some very powerful mk1 machinery run with standard GTi setups and do not suffer any of the issues related to high cornering Gs and fuel starvation.

    After my mk1 started to suffer the dreaded fuel starvation at the last Curby event, I started to investigate what was going on as prior to this, my mk1 didnt have this issue.

    Upon removing the fuel level sender from the tank, it is possible to see the in-tank fuel swirl pot. In the centre of the swirl pot, the factory gauze filter can be seen. This can be removed with a hook or pliers.
    IMG_2528.jpg

    How it works is that the fuel from the tank passes through into the centre of the filter from where it heads downwards towards the rubber sealing disc and then gets sucked out of the tank along a pipe to the tank outlet.

    Here is the bottom of the swirl pot showing the sealing disc location and fuel pickup hole along with fuel return.
    g1tankinternals1.jpg

    So what has happened to my tank? Well, upon removing the filter, I found the bottom of the swirl pot to be full of dirt and rust particles present from a previous filler pipe rupture with resulting dirt and flakes of rust being sucked into the swirl pot.

    Using a flexible magnetic pickup, I proceeded to remove all the flake of rust until the area was clean as possible. But as the dirt was removed, it became apparent that the rubber sealing disc had broken down and become perforated. Using some pliers, I removed the damaged disc. The problem that leaves me with is that the swirl pot no longer has a sealed bottom so thus drains itself back into the tank in was filled from. So instead of the fuel pump receiving a steady flow of fuel from the swirl pot on hard corners, the swirl pot empties itself out leaving the pump to run dry and starve the pump of fuel.

    The thing is that the swirl pot is not removable from the tank without cutting the tank open and the rubber disc cannot be fitted without removing the swirl pot.

    So unfortunately that leaves me with one conclusion. The tank is kaput! I can now either try to find another 2nd hand tank, which will be like walking through a minefield, or fit some expensive after market pumps, external swirl pot and pipe work. I hope others find this info helpful.

    Also a big thank to Aminder and Chris Eyre on helping out on this along with others too.

    Regards,

    Gurds
     
  2. A.N. Other Banned after significant club disruption Dec 5th 2

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    Brilliant - at least we know what it is. Damn rubber seal.

    Sorry I missed your last call yesterday.
     
  3. jamesa Forum Junkie

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    My GTI starvation problem was easily cured - keep the tank > 50% full
     
  4. vw_singh Events Team Paid Member

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    Lol. That doesn't really cure the problem now does it? :p

    Gurds
     
  5. jamesa Forum Junkie

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    Which problem exactly ?

    Rust in tank - non everlasting rubber disc - VW poor design - over enthusiastic driving ;)
     
  6. vw_singh Events Team Paid Member

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    Fixing the problem would be to restore original function, i.e. being able to take tight right hand corners with fuel levels lower than 50%. Currently I only see two real solutions which are a new replacement tank or fitting an external swirl pot and associated parts.

    You have only stated some of the causes of the problem. But thanks for your input.

    Gurds
     
  7. Mike_H Forum Addict

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    Drain the tank and seal the disc in with fibreglass resin / liquid rubber / hermetite / other? Need to find something that's not attacked by the petrol.

    Re-reading your post, surely if you got it out without cutting the tank, you can get it back in?
     
    Last edited: Jul 1, 2009
  8. vw_singh Events Team Paid Member

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    The thing is Mike, I managed to remove the damaged perforated section but not all of it. It kinda ripped out unevenly. As the underside picture shows, the disc extends under out larger than the area accessible from above when the filter is removed. Also, I think I read somewhere on vortex that the part isn't available? But would need to check for certain.

    I thought about sealing the area back up as you described but the method runs the risk of either blocking up the fuel pick up or not sealing the originally sealed area properly.

    Gurds
     
  9. micky1 Forum Member

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    think this should be tidied and made a sticky?

    Good info and insight into a mk1 gti tank.
     
  10. A.N. Other Banned after significant club disruption Dec 5th 2

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    Agree - it's all good stuff.
     
  11. aminder

    aminder CGTI Committee - Webmaster Staff Member Admin

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    STICKY!!!!


    I left my cardboard drip tray at your house ;)
    Guess I'll just have to change the sump now.
     
  12. Mike_H Forum Addict

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    Can you get your fingers underneath the swirl pot?

    I was walking to the shops last night, thinking about this, and I'm not 100% convinced that the little hole in the rubber is really the problem, although I'm struggling to think of a credible alternative.

    I guess if you fit an external swirl pot, the problem should go away.
     
  13. A.N. Other Banned after significant club disruption Dec 5th 2

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    Spoke to vw_singh about this earlier in the week and came to the conclusion that the swirl pot has to be leaking.

    Had this with another car - swap the tank for an identical one, fuel surge issues on right handers went away, albeit not a VW. No discenible difference between the two tanks.

    To me, an external swirl pot is just unncessary luggage.
     
  14. Mike_H Forum Addict

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    Agreed, but easier than swapping the tank, only to find you've got the same problem.
     
  15. aminder

    aminder CGTI Committee - Webmaster Staff Member Admin

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    Rubber seal is definitely the problem lad, yeah the external swirly pot "should fix" the issue and will look wicked!!

    I'm sure Gurds (Vw_singh) will update us once he's fitting his equipment.
     
  16. vw_singh Events Team Paid Member

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    I would really like to re-seal the area to make sure that the problem lies with the seal but I don't have time to chance ruining the tank completely at the mo. I am draining the tank again on Saturday so I could pour fuel directly into the swirl pot area in a completely empty and dry tank to check wether the fuel pours out of the outlet or leaks out into the tank.

    Gurds
     

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