morning start problems and air bubbles in the fuel line

Discussion in 'TDi - SEAT Diesel specific topics' started by cypher007, Nov 24, 2009.

  1. cypher007

    cypher007 Full Member

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    weve got an 03 Seat Toledo which has a constant stream of air bubbles running along the transparent fuel line. once the car is started it doesnt seem to affect performance, but heres the wierd thing:

    start after 8hr day at work OK.

    start in the morning, hmm, needs at least 2-3 goes, it just catches then stops, before it finally starts.

    ive bought a new fuel filter, £24 HOW MUCH!!!, and the plastic T piece £20 HOW MUCH!!!. so before i fit the T piece id like to know if it is probably going to be an air leak here, or if i should be looking elesewhere. the VW stealer said it could be the electric lift pump, cant see this myself as how does that equait to getting air in the fuel system.

    one other note, the garage that used to service it said the reason they fitted a new fuel filter and two cans of fuel cleaner was becuase:

    the previous owner tried some bio-diesel, hmm.
     
    #1 cypher007, Nov 24, 2009
    Last edited: Nov 24, 2009
  2. MJ

    MJ Public transport abuser

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    Possibly glow plugs or injector seals, a little air in the fuel lines can be normal.
     
  3. cypher007

    cypher007 Full Member

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    i have replaced the glow plugs, only to find out they dont actually come on until about 5c. the injector seals, hmm, would this mean fuel is slowly seeping into the cylinders? as it is quite smoky when it does catch, but it soon clears.

    the bubbles are maybe 10-30mm long depending on if its running or not.
     
  4. yorkie1

    yorkie1 Guest

    air in the fuel would be a problem for starting must be sucking air from somewhere or fuel could be leaking back to tank could try a non return valve?
     
  5. Muttley

    Muttley Catch that diesel!

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    The TDI 110 engine isn't PD and doesn't have a lift pump.

    The T-piece, if it is the one that fits in the fuel return line on top of the filter, is a thermostatic valve that lets hot fuel into the filter to speed up the thawing out of the fuel going to the engine on cold mornings. So it isn't just a bit of pipe :)
     
  6. Andrewcupra TDI

    Andrewcupra TDI Resident Desk Jockey

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    this seems to be my problem too , only i cant see bubbles
    but mine doesnt want to restart when hot,

    i do get a cloud of white ish smoke on first start
     
  7. cypher007

    cypher007 Full Member

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    ahh cheers Muttley. the reason i was going to replace it was because it has an O ring and i wondered if air could be being sucked in around the O ring, and then fed to the main fuel line to the pump via the top of the filter?
     
  8. JR_130

    JR_130 Full Member

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    My Dad had this until recently when he got the fuel temperature sensor replaced on his Octavia, way easier to start when hot now.
     
  9. MJ

    MJ Public transport abuser

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    I think andrew's tried everything under the sun to resolve his issue mate, including his fuel temp sensor.
     
  10. Andrewcupra TDI

    Andrewcupra TDI Resident Desk Jockey

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    yep you rite there, has been suggested crank sensor or camshaft sensor ,
     
  11. cypher007

    cypher007 Full Member

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    it was really bad this morning

    this morning it was really hard to start, and yet the glow plug light came on for a little longer than usual, as the outside temperature was 4.5. so im guessing even with glow plugs running its still got big problems somewhere.

    could i have a blocked/restricted intake? i set the EGR to 33768 to close it using vagcom, but the car had already covered 65k when i bought it.

    i wondered about using some of those 10k foam treatments through the intake.
     
  12. rallynut

    rallynut Full Member

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    just a bit of info for you all,
    my work van a mitsibushi l200 had the same problem as all of you are mentioning along with lack of power poor starting both cold and warm but worse when warm and after changing loads of parts it was a faulty relay that the glow plugs use thats about all the info the garage gave me at the time i picked it up as i spoke to the receptionist,
    maybe of use to you.
     
  13. cypher007

    cypher007 Full Member

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    hmm

    tomorrow morning i might, if ive got time, check the supply to the glow plugs, as it should be cold enough to bring them on. is there any way of increasing the temperature at which the glow plugs are turned on? maybe taking it up to 15c.
     
  14. cypher007

    cypher007 Full Member

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    ok an update

    weve replaced the fuel filter and the T piece. it still got bubbles in the fuel line [:@] . so now weve tried feeding the filter from another piece of pipe and still bubbles. so the air is getting in on the return side somewhere. any ideas?
     
  15. brad1

    brad1 Guest

    Mine has bubbles, not loads, but you do get bubbles in the fuel line, and mine starts up rough on cold mornings, doesnt struggle to start, but splutters once, i think maybe a on the way out glow plug relay ;)
     
  16. JamesL

    JamesL Senior Member

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    mine has bubbles. Got one when my cambelt was done and then a few more when I changed the fuel filter :D
     
  17. cypher007

    cypher007 Full Member

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    update

    right the guys here in motor vehicle have found, that with the T piece removed from the filter, the T piece socket blanked off, and feeding the filter direct from a bucket of diesel, weve still got bubbles. so the air must be getting in around the edge of the filter or the drain off.

    anyway i took the new filter back to the VW dealer and they wouldnt change it [:@] . they said i would have to buy a new one and then wait for a refund from VW if they found a fault with the filter. this sucks and im sure is against trading standards. how do i sort them out?

    at the moment ive got the old filter refitted with the new T piece, and ive still got a few air bubbles :( .
     
  18. cypher007

    cypher007 Full Member

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    ok

    just read a post on another forum, which basically said that the IP is stong enough to pull air past the hose clips. so i think ill go and get some of those fuel line clips that have like an overlap so they dont oval the pipe, and see if that cures it.
     
  19. ralph

    ralph Full Member

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    before you do that try smearing a bit of vaseline round the hose connections on the fuel filter.

    Mine has air bubbles in the fuel line and it does not like a cold start but it does not sound like its as bad as yours, Mine fires up pretty quick and just chugs for a few seconds.....only when the temps are pretty close to 2degC or lower. It was still starting like that at minus 6 last year though so I will just live with it
     
  20. cypher007

    cypher007 Full Member

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    update

    right ive found if i turn the ignition on and off twice on the third turn it will start and run. so i think i need to extend the glow time in the ecu, and the temp the glow plugs come on at. is there a way of doing this with vagcom?
     

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