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Dying bus after highway driving

Discussion in 'T3 & T4 Tech Help Clinic' started by Dapom, Jun 7, 2015.

  1. Dapom

    Dapom Well-Known Member

    Messages:
    805
    Location:
    Brisbane
    Hey all!
    I'm going through the long process of sorting all the things wrong with my bus to try and eliminate a problem he's had since buying him.
    After a decent highway drive at 100ish kph for about 15mins, when I get onto back roads,so more gear changes lower revs etc, he loses power. I don't get dash lights coming on. If I clutch it and put foot flat to floor he will 'clear' and drive fine for a bit. If it gets to the stage where he dies completely, it takes about 15secs of cranking to get started and then will run fine :-/
    I have....in no particular order.....fixed all vac leaks I can find, cleaned throttle body and airbox + pipes, new exhaust (old one fell off), new fuel pump and filter. Fuel lines and new tank were done recently by po.
    I'm now thinking that it's a vac lock on the tank maybe? He overflows on fill up and I get a small amount of 'overflow' from under passenger side wheel arch. Would the vac/balance hoses under there being not quite right cause the issue I'm getting?
    Any ideas appreciated. It's frustrating as he drives so well most of the time and then when he does this I lose confidence in him again.
    Thanks in advance :)
     
    Last edited: Jun 7, 2015
  2. Barry

    Barry Well-Known Member

    Messages:
    6,191
    Location:
    Abbotsford NSW
    Sound like the "plugs" or the "T piece things" in your tank are shot
    Doubt it causes problems - i had this and my van ran fine.

    Except petrol comes out when you fill up.

    Does it run hot?
     
  3. Dapom

    Dapom Well-Known Member

    Messages:
    805
    Location:
    Brisbane
    Seems cooler than my bay used to run.....haven't got temp sensor yet but I never go looking for burning stuff coz it smells hot and used to do that a lot with my bay lol
    I suppose I was thinking the hoses etc around the tank area as I know they're not right though I know tank is new. Feels like a fuel starvation problem. Though having said that if I have foot flat to floor up a long hill then it feels like it's flooding. Only just thought about that!
     
  4. Mark Fonderie

    Mark Fonderie Member

    Messages:
    74
    Location:
    Hobart
    This could be Vanagon syndrome ...Do you have the harness that goes to the AFM?
    upload_2015-6-8_17-55-43.png

    Another possibility is the fuel relay - if they are on the way out they can die when the engine gets hot.
     
  5. Dapom

    Dapom Well-Known Member

    Messages:
    805
    Location:
    Brisbane
    Hey Mark. Thanks for your thoughts. I have considered intermittent syndrome but was under the impression it only affected later models, around '85 on with WBX?
    When I replaced fuel pump I did the full Bentley test of the dbl relay and all tested ok, though it would've been cold at the time so that's def something to bear in mind. Though if it is a heat affected dbl relay would it start again and drive fine straightaway as relay would still be at same temp..?
    Thanks!
     
  6. syncro

    syncro Well-Known Member

    Messages:
    10,371
    Location:
    Southern Highlands
    Does not apply to air-cooled.
     
  7. chewtah

    chewtah Guest

    The post on the cut open fuel tank might be a clue, blocked filter in the tank?
     
  8. Dapom

    Dapom Well-Known Member

    Messages:
    805
    Location:
    Brisbane
    I read that thread.....checked the history and the tank was replaced with new last year so should be no filters in it...did notice at the weekend that the drivers side expansion tank is missing lol just...not there! There should be one right? Probably not the problem but an indicator that maybe fuel tank and associated hoses might need some checking ;)
     
  9. vince4kc

    vince4kc New Member

    Messages:
    4
    Location:
    Sydney
    Any update on this Dapom? Sounds like what I have with a fairly recently squires 85 1.9 WBX I have. Never had these symptoms with my 89 2.1, and I too thought it was the "syndrome" ...until I installed the adaptor and there was no change. Am now reduced to thinking perhaps some water in the tank? Any news with your T3 would be appreciated.
     
  10. Dapom

    Dapom Well-Known Member

    Messages:
    805
    Location:
    Brisbane
    No unfortunately no news as yet :( havent had anytime to go look at it. Hopefully I'll get a chance over the next week or so...
     
  11. Grantus

    Grantus Well-Known Member

    Messages:
    18,849
    Location:
    Southern ACT
    Are you sure it's fuel related Dapom?

    I've very little aircooled experience, but just a guess, wouldn't a faulty ignition coil when hot, possibly cause the same symptoms......:rolleyes:
     
  12. Kai

    Kai Well-Known Member

    Messages:
    4,794
    Location:
    Sydney, NSW
    I agree, it happened to me only a month ago.
     
  13. hairyman

    hairyman Active Member

    Messages:
    411
    Location:
    Sydney, NSW
    I had that sort of problem and it was the coil. I'd get half an hour then it'd run bad at idle however would restart after 5 minutes to cool down.

    The coid was a replacement part from Just Kampers and was only 6 months old but it was crap compared to the Bosch coils. I changed back to a Bosch coil and it's all good again. I could hear the oil sloshing about in the repro coil when I took it out so it must have been overheatkng and leaking or boiling it off.
     
  14. AC-T3

    AC-T3 Well-Known Member

    Messages:
    1,137
    Location:
    Woy Woy
    As posted a moment ago: Electrics most likely - coil, condenser and HT lead from coil to distributor that can break down under load when hot. The injectors are triggered by the ignition pulse so no or poor ignition then no or poor injection. Until it all cools down and magically resets. A run down battery can do the same - enough energy to crank but not enough to feed and fire.
     
  15. Dapom

    Dapom Well-Known Member

    Messages:
    805
    Location:
    Brisbane
    Would that not make it a problem that arose every drive though? Prior to this incident I had been daily driving for a couple of weeks without so much as a cough. It's the same problem that I started with when I bought the van...been fine for months and months then back it comes :-/
     
  16. Grantus

    Grantus Well-Known Member

    Messages:
    18,849
    Location:
    Southern ACT
    A spare coil is not that expensive, and easy to install when the problem happens again, to see if it's an instant fix....:rolleyes:
     
  17. AC-T3

    AC-T3 Well-Known Member

    Messages:
    1,137
    Location:
    Woy Woy
    No not necessarily so, these problems can be intermittent and hard to diagnose. For example, the windings in a coil can break but still retain contact under normal use but when things get hot and then wires expand then the break becomes a real break and no flow. Let it cool down and all is good until next time. Load produces heat. The same goes for the condenser - had one do just as you explain - until replaced. Suggest slowly working through each component in turn
     
  18. Dapom

    Dapom Well-Known Member

    Messages:
    805
    Location:
    Brisbane
    Awesome info! Thanks so much everyone. Will start collecting the various parts and switching them out till I get a fix :) will keep updated coming as they arise :)
     
  19. Dapom

    Dapom Well-Known Member

    Messages:
    805
    Location:
    Brisbane
    Soooo...one thing I've neglected to mention is that it's got electronic ignition....am going to go through the history to try and find out how old it is. The 'pickup' in the dizzy is red abd coil has no markings but is in the same red and looks newish. Will update when I find out what setup it is and how old.
     
  20. hairyman

    hairyman Active Member

    Messages:
    411
    Location:
    Sydney, NSW
    New parts can be worse quality than the original parts. I put electronic ignition on my old beetle and replaced the coil with one from empi. It was nice and shiny and lasted a few months before it failed and I swapped if back to the old Bosch coil. No problems after that. Get your hands on agood coil (Bosch) and see if that clears it up
     
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