Problem with idling?

Discussion in 'Fuel System & Electrics' started by Annie G, Nov 24, 2016.

  1. Annie G

    Annie G New Member

    Messages:
    21
    Location:
    Sydney
    Hi all,
    I'm having a strange intermittent problem with Gus, 1976 bay. Occasionally after re-starting the engine it will not idle properly. The idle becomes very low, until it is almost stalling, and the generator light is glowing. The idle is also very lumpy. When it first happened my husband found that two of the connections to the + and - on the coil were very loose, so he crimped on new connectors, and it was fine after that. However, after driving last Friday in 37 degree ambient temperature the idle once again got very low and I had to keep blipping the throttle to keep it running at idle.

    My husband says that he has checked that the choke heater elements and the idle control valves both have 12v feed to them, and they all click when 12v is applied. Husband thinks that when the intermittent problem occurs the mixture is too rich and is wondering if somehow one of the chokes is not functioning properly. He says that that the heating element in the choke heats up and moves a lever that lifts the choke butterfly so that the mixture is not enrichened. He thinks maybe a heater element is intermittently inoperable? Husband is very experienced on aircooled motorcycle engines but Gus is a learning curve for him

    He also had a look at the vacuum pipe to the front brake booster but he thinks that is OK and anyhow if it was split he says there would be a permanent idle problem??

    Can anyone offer any suggestions. 95% of the time Gus runs perfectly and idles like a champ.
     
  2. splitbus

    splitbus Well-Known Member

    Messages:
    3,250
    Location:
    Brisbane
    Check your rubber elbows on the balance pipe, under each carby, repo ones are a softer rubber, when they get hot they expand and let air in, put some clips on them, this could ?? be your problem


    Or your coil is on its way out
     
  3. Mellow Yellow 74

    Mellow Yellow 74 Active Member

    Messages:
    759
    Location:
    Sydney
    If it only happens when it is not warmed up it could be a choke element - you can just unscrew them and check if they look ok. Like split us says the balance pipe elbow or other vacuum leak is also a contender but I would have though this would give rough running all the time. Otherwise I would check timing, points, plugs etc or if you don't drive it much stale fuel can give weird running symptoms.
     
    Maxa1967 likes this.
  4. Db7gtgrigio

    Db7gtgrigio New Member

    Messages:
    27
    Location:
    Sydney
    I am the husband. Thanks for the tip on the balance pipes will check. Is there any way to check the coil. Most of the time the bus runs well and revs well, so thought coil was fine....

    Also, it only happens when engine is warm. It feels like the choke is sometimes not turning off. Wondering if it is possible for the element to somehow be intermittent
     
  5. cbus

    cbus Well-Known Member

    Messages:
    10,570
    Location:
    sunshine coast
    Engine cold.
    Loosen the 3 screws on the face of the choke bodies and turn untill butterflys are vertical.
    Check that they are retained in close to vertical position.
    This ensures they are disarmed and will eliminate from the equation.
    Retighten screws.
    You may need to remove the rods that connect from accelerator cross bar to carb to access one of the screws.
    They just pull off.
    If it runs like crap afterward , you have forgotten to reconnect both rods. :)
    You can run like this for summer if you wish.
    Will just need a bit longer warming up.
     
    oldman likes this.
  6. Db7gtgrigio

    Db7gtgrigio New Member

    Messages:
    27
    Location:
    Sydney
    I checked the rubber hoses connecting the balance pipe between the 2 carbs. The hoses are the original braided type and don't appear cracked. I did also discover that the large hose leading to the airbox from an inlet above the statying battery had fallen off the airbox. The corrugated pipe (probably original) is hardened and needs replacement. I did however manager to secure it back on with a pair of large hose clamps and Gus seems to be idling nicely. Could be coincidental, time will tell, but could that hose not being attached cause low idle condition???
     
  7. KahunaKombi

    KahunaKombi Super Moderator Staff Member

    Messages:
    17,696
    Location:
    Bracken Ridge, Qld
    Rubber hoses where fuel (fluid or vapours) flow through will rot from the inside and she from the outside. What may look ok outside can reveal the opposite inside - feel and if firm or tacky to touch = replace.

    Some of the cloth braided hoses these days will not last with today's fuels so try to find something modern or talk to your mechanic ...... better quality/better life
     
  8. leithbro

    leithbro Member

    Messages:
    564
    Location:
    Cairns
    Just a thought - have you had a look at your plugs? You might find the change in temperature / humidity is causing your air-fuel ratio to go out and your plugs are fouling. I've changed to the 3 prong plugs like this:

    http://vwparts.aircooled.net/NGK-BP6ET-Spark-Plug-14x3-4-Reach-Threads-13-16-p/bp6et.htm

    I also run a pertronix electronic ignition instead of points and a flamethrower coil which I believe help. I've got 40IDF Webers, so no choke on a 1776 type 1 and live in the tropics. The car runs noticeably different up on the tablelands where it is cooler but elevated than it does at sea level, and if it was an aircraft you'd lean out the mixture if ambient was hot/humid or at altitude.

    For whatever reason I tend to see it most on #3 (although I think I have it pretty dialed in now).

    I'm sure someone will weigh in here and explain why that is, but it's definitely worth pulling your plugs if you haven't already.
     
  9. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    2,604
    Location:
    Penna, Hobart

    probably not. That pipe is the air inlet to the filter box and many have run for ages with it but it is better to have it.

    In a standard set up the balance pipe has another pipe that goes up to the idle circuit on the left carb (as you are looking at the motor from behind the bus). All 3 pipes (plus the small one mentioned further on) join under the fiterbox. The idle circuit feeds the idle mixture of air and fuel down this pipe to bypass the butterflies in each carb. There is a small rubber tube that come of the central point under the filter box which then goes to a valve on the right air horn. Some times this is blocked off. In a properly tuned engine (with the carbs, balanced, set up and in good nick, the timing perfect, the valve clearances right etc etc.) you should be able to pull that little pipe off and the revs should not decrease or increase. It will sound different but the speed should not change. If it goes up you are too rich, down and it is too lean.

    Back to your problem - with a leak in the balance pipe the mixture will be leaned out by the extra air so the revs will drop and it will run rough. When you rev up, the main jets take over and it will run pretty much normal, maybe a little lean dependent on the balance pipe leak, as the vacuum in that line will be less.

    Have a look at this as, although as is mentioned further down it apparently isn't as easy as the official one (no-one seems to have a copy of anymore) and it does give you an idea of how the system works. I have tried to tidy it up and remove some of the American references to make it more accurate in my copy of it, but it is really window dressing compared with this.

    http://forums.kombiclub.com/threads...pe-iv-adjustment-procedure.45512/#post-488549


    Good luck

    Adrian
    .
     
  10. Db7gtgrigio

    Db7gtgrigio New Member

    Messages:
    27
    Location:
    Sydney
    Well I think I have sorted the idle problem. The fuel shut off solenoid on the rh carb was loose. I nipped it up with a 9mm spanner and over 500km the idle has been spot on. Thanks all for the suggestions
     
    cbus likes this.
  11. TheKing

    TheKing New Member

    Messages:
    11
    Location:
    Bonny Hills
    Hi all, I also had this issue last weekend, however not long being serviced I could rule out points, leads etc. I spoke to my machanic . He advised me to check two things first. 1 the rubber elbows on the balance pipes 90 degree, make sure they are not split or perished and 2 take out the fuel jet on the side of each carbi ( 9mm/10mm) brass piece. Brush clean jets and also compressor blow out jet and jet hole in carbi( also take off air filter to see into top of carbi) check holes are clear. I had to do this process twice, but it worked. Good one to remember when trouble shooting
     
  12. chris taylor

    chris taylor Well-Known Member

    Messages:
    1,298
    Location:
    adelaide sth aust
    Same problem with mine, had a quick look and found the vacum hose had a big split where it attaches to the distributor , dont know if thats the problem, but seeing whats written here gives is giving me other thoughts .
     
  13. chris taylor

    chris taylor Well-Known Member

    Messages:
    1,298
    Location:
    adelaide sth aust
    I have replaced the vacuum hose but still having issues , further inspection revealed the vacuum advance was not working due to a split in the diaphragm in the vac advance unit which has now been replaced, this was found when Steve could not correctly set the timing. Do not know if this has anything to do with the idling problem.
     
  14. chris taylor

    chris taylor Well-Known Member

    Messages:
    1,298
    Location:
    adelaide sth aust
    To all those people who have been having the same type problem as i have had maybe these few words may help ,?? { i suspected at first that there may have been an ethanol problem and i still cannot rule that out } ??? , small things that you would not normally look at ,or for that matter, know about , can cause major problems and be the cause of big headaches , the fuel enrichment startup solenoid on the side of the l /h carby gave up the ghost but had that fixed, further searching found (1) the diaphragm in dist vac advance was split so no vac advance, (2) the air cleaner housing where it sat on R/H carby had a big crack in it so would have been sucking in cold air not warm . (3) The vacuum thing in the air cleaner ,yes ,inside the air cleaner, was not working either so the flap was not doing what it should have been doing , opening and closing as required . all these things have now been rectified , fingers crossed problem fixed, these are just some of the things you may want to look at .
    hope this info maybe of some help..
    Went for a 200 kl drive on Saturday and ran the way i thought it should , no misfiring or rough idle, pulled well through the hills.
    Chris T
     
    Last edited: Aug 13, 2017
    Timc91, Mordred and David H like this.
  15. chris taylor

    chris taylor Well-Known Member

    Messages:
    1,298
    Location:
    adelaide sth aust
    In regards to previous post I'm pleased to say that the problems I was having seem to have been overcome, now it is running normal once again , at least I know that when I take off next march I wont have those problems to worry about. I hope I'm not talking to soon...:(:(:(:(:(:(:(
     
    David H likes this.
  16. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    2,604
    Location:
    Penna, Hobart
    Great to hear. Sorry I dropped out for a bit, a few other things taking my attention and not one of them VW related.

    Adrian
     
  17. chris taylor

    chris taylor Well-Known Member

    Messages:
    1,298
    Location:
    adelaide sth aust
    hi Adrian hope all is ok for you. The next thing i want to do is go back to using 91 instead of 95 or 98, i originally thought it was a fuel problem but it turned out to be anything but that , i have noticed that using the higher oct seems to make the motor sound like its really working hard when it is not ,so will put it back to 91 for a while and see what happens.
     
  18. saabman

    saabman Well-Known Member

    Messages:
    4,705
    Location:
    Goulburn
    Chris I also find problems are rarely caused by one fault. It usually is the columination of a number of sometimes seeming unrelated issues that compound until the combination of all of the pushes things over the edge.

    Can be damn frustrating when trying to work it out but much better when it everything works as it should :cool:
     
  19. chris taylor

    chris taylor Well-Known Member

    Messages:
    1,298
    Location:
    adelaide sth aust
    hi Saabman, your so correct, had trouble believing what i was being told until i saw the proof,but at least mine is fixed now and is running as good as i can ever remember, MPG seems to have improved to ,from 22 to 24 mpg, not a lot but definitely on the right track
     

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