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Idles and runs then stalls

Discussion in 'Fuel System & Electrics' started by KombiEvie, Feb 11, 2019.

  1. KombiEvie

    KombiEvie Member

    Messages:
    91
    Location:
    Berkeley Vale
    My 76 bay will start and then stall ,then its slow in starting again
    Ive done all the checks and everything looks fine
    checked the vacuum hoses and all looks well
    Plenty of fuel
    Was running fine beforehand

    Any help would be great
     
  2. Barry

    Barry Well-Known Member

    Messages:
    3,820
    Location:
    Abbotsford NSW
    What motor?
    2L type 4?
    Dual carbs or fuel injection?
     
  3. David H

    David H Well-Known Member

    Messages:
    5,143
    Location:
    newcastle
    Unlikely to use even a blocked fuel filter of fuel so quick. Spark? & resistance be my chase.
    Cheers
     
  4. tintop

    tintop Well-Known Member

    Messages:
    559
    Location:
    Canberra
    If it's a carby model...
    Will it keep going if you keep it at higher revs (main circuit) or if you pump the accelerator (accelerator pump) and only die if it's trying to idle (idling circuit)? I assume the engine is cold - so the chokes should be closed.
     
  5. tintop

    tintop Well-Known Member

    Messages:
    559
    Location:
    Canberra
    Electrics - all wires tight to and from coil, distributor and carbies?
     
  6. cbus

    cbus Well-Known Member

    Messages:
    11,947
    Location:
    sunshine coast
    Checked dwell/ points gap/ timing ?
     
  7. Barry

    Barry Well-Known Member

    Messages:
    3,820
    Location:
    Abbotsford NSW
    Was anything done between running and not running?
     
  8. KombiEvie

    KombiEvie Member

    Messages:
    91
    Location:
    Berkeley Vale
    still have issues
    its a 2l with carbies
    whats happened today is after long cranking times it will run for a few seconds ,if you pump the pedal,it will run for a few more seconds then stop
    like the bowls are empty
    its may start easy next turn of the key or it may not
    no real pattern
    ive flatten my battery trying
    checked all wiring ,appears ok ,changed the petrol filter ,it was dirty but the problem didn't change at all
     
  9. KombiEvie

    KombiEvie Member

    Messages:
    91
    Location:
    Berkeley Vale
    the problem only appeared when I thought the petrol was low and I added more fuel
     
  10. tintop

    tintop Well-Known Member

    Messages:
    559
    Location:
    Canberra
    I'd take a hose off and see if the fuel pump is pumping (enough).
    Alternatively you could fill the carbies through the top breathers and see if it runs that way...and work backwards from there
     
    David H likes this.
  11. David H

    David H Well-Known Member

    Messages:
    5,143
    Location:
    newcastle
    How was this done & from what container/fuel age?
    Cheers
     
  12. oldman

    oldman Super Moderator Staff Member

    Messages:
    8,698
    Location:
    Avalon Beach NSW
    I’d be draining the bowls on each carb. and checking for crap beyond the disposable filter......
    Cheers,
    Mark
     
  13. cbus

    cbus Well-Known Member

    Messages:
    11,947
    Location:
    sunshine coast
    Yep.
    And clean the valves into the bowls.
    Keep old ones if possible as a lot of new ones are not much chop.

    Do a fuel level check by running engine, turn off , carefully remove top of carbs, measure from carb bowl top edge down to fuel.
     
  14. KoDan

    KoDan New Member

    Messages:
    6
    Location:
    australia
    I thought I would add this symptom because although Dr Google has given me lots of information I've yet to find these exact symptoms of an unhappy kombi described except as parts 2 & 3 of the above quote from tintop!

    Over just a couple of days the the wifes 'new' 77 bay went from: running perfectly fine to > stalling at lights > now undriveable. Frustratingly it starts easily and runs but *only* the throttle is being pumped, it just dies at idle or at any *static* throttle position (ie 1/2 full throttle). Starts & revs fine so timing/spark seem OK but clearly it's only getting fuel via the carby accerator pumps.

    FYI the electric chokes aren't operating great (only rh carb butterfly closes when cold) but these aren't the issue IMHO.


    I have read up on the carby (twin Solex 32-34 Type 3.) setup and have checked the obvious, especially the Central Idling Circuit and the brake-assist circuit joints, however I realise that small leaks are impossible to track down without a second pair of hands and a vacuum meter. However there is nothing *blazingly* obvious (ie. loose clamps, cracked hoses) so I'd still be surprised if a 'non-visual' air/vacuum leak can create so much havoc.

    Maybe it can?

    I thought I could easily isloate the brake circuit by blanking off the entire circuit at the manifold elbows - however the car did not like that at all, definitely ran worse and I'm guessing richer (backfires). This makes no sense to me but I tried it *twice* and blanking off this circuit here defintely has an effect on how the motor runs.

    If anyone can illuminate me as to how a vacuum takeoff can be affecting the engine would be greatly appreciated!

    I was actually wondering if it was the mechanical fuel pump or maybe the coil or maybe the planetary alignment of Jupiter, but since our local mechanic has a 3 week wait I thought perhaps pulling the carbies off to check the main jets might be worth a shot. I ran the machanic to ask about 'missing' idle cut-off valves and a carby rebuilder, however he said that with these symptoms it's highly unlikely that the carbys are the problem. In fact he thinks it is so simple that he's even happy for it to be trucked in because he can fix it same day.

    Which is great, but it's still very frustrating.....I'll add another post when it get fixed.
     
    David H likes this.
  15. T1 Terry

    T1 Terry Well-Known Member

    Messages:
    1,370
    Location:
    Mannum South Australia
    The vacuum pipe for the brake booster also acts as a balance tube between the 2 carbies, so if blanking it off results in a backfire you either have very out of balance carbies or no idle fuel one side or a serious air leak causing a lean run one side.
    A can of spray carby cleaner is the easiest to sort these sort of issues. With the engine running but poorly with the brake pipe ends blanked off, spray a whiff down each carby and see which side has the better result. This will indicate which side is the trouble.
    Drop the throttle linkage off each side of the cross rod and see if both links go on without moving the throttle plate or the cross rod. This will give you an idea if the throttle linkage is causing part of the problem.
    Next, start the engine again and spray around the carby and manifold on the side that improved the most when you whiffed a bit down the carby throat. If this improves the engine run a bit you can isolate where the air leak is.
    If this didn't improve things, look for an electric solenoid hanging out the side of the carby about halfway up or a brass jet with a hex head screwed into that area (the solenoid has been eliminated) take that out while keeping the engine running and put a finger over the hole to stop the vacuum leak. It will run very rich but that will at least wash out the idle circuit. Check the brass jet and see in the small hole in the centre is clear, don't try to drill it out or run an oxy tip cleaner through it because your fuel economy will suffer a serious blow if you make that hole bigger.
    If putting the jet back in reintroduces the backfiring, try swapping the jet from one side to the other carby, does that move the problem? If yes the jet is still blocked, if no the carby idle circuit is the problem.
    If none of this works, grab a cold beer and watch so tv or something, this is just not your day :lol:

    T1 Terry
     
    David H and Wayne murray like this.
  16. KoDan

    KoDan New Member

    Messages:
    6
    Location:
    australia
    Thanks mate. Yes I have since been told it is primarily a balance tune, which makes perfect sense when you consier it is 13mm & on both sides - which even for the Germans would be overkill for just a vaccum takeoff!

    Apart from the fun of tow trucks etc., the problem did turn out to be a relatively simple fix, but I also think a rather uncommon issue. In the casting holding the CIC solenoid are two little (~10mm dia) welsh plugs - not shown on carby schematics nor can you see them because they face the bulkhead. One had simply fallen out letting tons of air into the idle circuit.

    Even the kombi mechanic said he was a bit stumped when the obvious (and well documented here) air leak fixes didn't work, especially when he had also pulled out and checked the idle jets. FYI these have replaced the original solenoids - advised this is perfectly fine unless engine runs on after turning off.

    So all-in-all a pretty easy 'fix' with some araldite (he actually found the welsh plug in the engine bay), but I don't feel a total dill for not being able to diagnose this one :)
     
    tintop and David H like this.
  17. T1 Terry

    T1 Terry Well-Known Member

    Messages:
    1,370
    Location:
    Mannum South Australia
    Ahhhh...... the carby cleaner spray would have helped locate the problem, but being such an unusual one it wouldn't be something you would actually look for or realise the hole shouldn't be open. good to here it is now sorted and yet another thing to add to the poor idle diagnostics file for future reference.

    T1 Terry
     
    tintop likes this.
  18. cbus

    cbus Well-Known Member

    Messages:
    11,947
    Location:
    sunshine coast
    Yep. Fix is fine and it's worth having the mechanic give it the once over as well to check for any other lurking issues.
    Someone knowledgeable looking at it in the flesh is always better than remote diagnosis.
     
  19. KoDan

    KoDan New Member

    Messages:
    6
    Location:
    australia
    Thanks mate. Yes I have since been told it is primarily a balance tune, which makes perfect sense when you consier it is 13mm & on both sides - which even for the Germans would be overkill for just a vaccum takeoff!

    Apart from the fun of tow trucks etc., the problem did turn out to be a relatively simple fix, but I also think a rather uncommon issue. In the casting holding the CIC solenoid are two little (~10mm dia) welsh plugs - not shown on carby schematics nor can you see them because they face the bulkhead. One had simply fallen out letting tons of air into the idle circuit.

    Even the kombi mechanic said he was a bit stumped when the obvious (and well documented here) air leak fixes didn't work, especially when he had also pulled out and checked the idle jets. FYI these have replaced the original solenoids - advised this is perfectly fine unless engine runs on after turning off.

    So all-in-all a pretty easy 'fix' with some araldite (he actually found the welsh plug in the engine bay), but I don't feel a total dill for not being able to diagnose this one :)


    Cheers Terry - how's the weather up there in Mannum? I'm at the end of the river - Goolwa! A realise a significant disadvantage was that it was just me trying to diagnose the issue, so I couldn't even get to the engine bay with the motor running. Still was a tricky one, and any case it's a useful addition to the knowledge pool.

    And speaking of knowledge - I had always assumed it was 'welsh' plugs (and have always actually wondered why) and have only just realised it is actually 'welch' plugs! Who says you can't teach an old dog new tricks! The reason I have clarified this is for search engines. If you ask Dr Google for 'welsh + solex' you don't get anything useful, but 'welch + solex' does give you some insightful links. Of course you have to 'know' to search for 'welsh/welch' plugs in the first case.....

    As always the answer to everything is 42.......you just have to know what is the actual question!
     
    TeeBee likes this.
  20. KoDan

    KoDan New Member

    Messages:
    6
    Location:
    australia
    True mate, but even the 'just VW' mechanic (who also regularly services the car BTW) though it was worthwhile having a clue as to how it all works. He says he always has vehicles being trucked in, from long-distances, for what are really simple fixes - especially with the CIC. IMHO if you choose to own 'old' stuff (garage includes 1978 Fiat X/1-9 & 1992 GPz900r) knowing how to sort the basics (eg. electrics) and some of the quirks is extremely beneficial unless you are a zillionaire. I'm no VW expert, but IMHO when you have an engine that starts, runs AND revs fine (so spark, fuel & compression) but just won't idle or hold revs it's unlikely to be anything major.

    And with a 3-week wait to see the mechanic I'm going to have a peek.


    In my case I learnt about the Solex setup, discovered why idle cut-off solenoids are OK being replaced with jets, replaced a broken LH carby throttle spring, identified up that the LH electric choke wasn't closing, and discovered the RH accelerator pump was being held on by just one tight screw. Another was loose, another had fallen onto the ground and the last one was only Ben Pon knows where. The mechanic said that he had never heard of that happening (generously donated a screw) but also said that these are old vehicles and over time vibration loosens most things - so almost anything is possible. Words of wisdom. Getting under the bus to check the brake boost line and tighten the hose clamps got me covered in grease but showed me why the kombi has no heaters, as not only are there no connecting hoses from the heat exchangers but the actual heater valve is missing! Ah well, summer is almost here.......

    But most importantly, because I was able to give the mechanics a pretty comprehensive description of the problem over the phone, they were confident they could fix it easily so were prepeared to squeeze the car in for a quick fix. These guys seriously know their stuff so they will always be used for both regular servicing & major fixes, but if I can sort the 'minor' glitches that inevitably will occur, with the help of forums, other expert owners and Dr Google, then I suspect that will make my wife's kombi experience a much happier one. :)
     
    micklyan likes this.

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