75 Bus Type 4 1.8 Engine Twin Carb does not want to start

[restocal63]

Samba to the rescue! Please Help! (Thanks before hand for reading this)

I have been working hard on my 75 kombi bus to get it back on the road after it has not been running for many years.

It is fitted with a stock Type 4 Engine AP Code having stock twin Solex Carbs.

I managed to get it running quite smoothly following all you precious advice found here, on Ratwells site as well from Colin Kellogg Amskeptic a started on the first turn always.

Started by replacing all fuel lines and fitting a filter from tank to fuel pump. Fuel in tank is clean.

Changed all vacuum pipes, brake booster elbows etc. as seen in the pictures, also rewired, the engine bay area feed to carbs (Central Cut off, LH Cut off, RH Cut off, choke & idle enrichment) and as per the precious help offered by Amskeptic. Fitted also a brand new Ernst Stock Exhaust as the old original ones was rusty and full of holes.

Recently wanted to tackle the various oil leaks I had from the engine (oil filler neck, valve covers and piston pushrod tubes o-rings) and also wanted to replace a faulty thermostat.

Last week replaced all the o-ring seals, adjusted the valves etc. no more leaks.

Bus started with out any problems (hot or cold as per previous many times) and idled around 850 rpm, with no hunting etc. Throttle response was good too and engine seemed powerful, as per previous tries.

After about 30 min running in idling to check the operation of the thermostat, then when revving up the engine noticed that exhaust seemed a bit sooty. Then engine idled again smoothly.

Upon revving up again the exhaust smoked black heavily, the engine back fired and the left hand brake booster elbow blew out of its place and then ran lumpy as there was a heavy vacuum leak.

Fitted hose clamps on the elbow, but the bus now refuses to start.

Checked points gap, still 0.4mm, static timing at 7.5 BTDC, check each plug one by one all fine, rechecked the valve gaps when stone cold, inlet set at 0.15mm, exhaust set at 0.2mm, but bus refuses to start. Rechecked compression on all 4 cylinders, 1-110 psi, 2- 115 psi, 3-115 psi, 4- 110 psi.

Fuel appears to be delivered from the carbs, although the spark seems weak.

Bus only started once with the HT lead for cylinder 3 removed and when installed back seemed to run worse, bus could not idle and ran very lumpy
in the 1500 to 3500 range however no sooty exhaust.

What could wrong? When checking the above I have never touched any of the carb settings, need to follow carefully Amskeptic twin carbs tune up instructions.

After this bus does not want to start.

Many, many thanks in advance for your help and input as I am lost.

[Tcash]

Upon revving up again the exhaust smoked black heavily
Sounds like it is flooding. Hold the gas pedal to the floor and try and start it.

Carburetor needle and seat cleaning

Good luck
Tcash

[restocal63]

Many thanks for your reply Tcash.

So if I understood correctly the engine is flooding as the carbs are 'leaking extra' gas and need to have their needles/cleaned replaced as necessary.

I need to dismantle these and refurbish them one by one.

My only concern are the initial base settings for getting it to start back.

Does anyone have any settings for the idle/air mixture etc.?

But before dismantling I shall try to restart it again and give it another try. The only thing which is worrying me and cannot find a logical explanation is why it had started with the HT lead for cylinder 3 removed and when installed back ran worse. Could it be a faulty plug? Shall put in new NGK ones just in case.

Could it be that a valve(inlet/exhaust) has some damage although the compression values look good?

Many thanks in advance for your inputs and suggestions.

[restocal63]

Managed to start the bus as per Tcash recommendations. (Big thanks again).

However it still runs roughly and does not idle properly unless I feather the pedal. Engine seems to lack power too.

Just uploaded a video to hear the bus running roughly.

https://www.youtube.com/watch?v=ltXokAgR4CY

What are you thoughts?

Big thanks again for your time to view this, help and input.

restocal63

[Abscate]

Check that the chokes, butterfly valves on top of the carbs, are open. I'm summer you won't need these but if they are stuck you will run rich and black smoke

Pop the air cleaner manifold off and take a look with a mirror, snap a pick so we can see how clean the carbs are

Don't mess with carb settings for a no- start, find rootcause first
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[SamboSamba22]

I faced similar issues a while back, had issues with carbs balancing and the bushing were leaking fuel pretty bad.
Sent carbs off to Tim at Volkbitz, and solved the leaking issue. Balancing took a lot more effort than I anticipated.
FWIW, Tim noted that the jet in the right side carb had a larger jet in it than the left, which was common place and stock for some applications from the dealer.
I also experienced a lot better idle and response once I did away with the flexible hose being used a the "carb balancing tube" and picked an original unit.
Stay at it, set your timing with both vacuum hoses off the distributor to about 28-32 BEFORE TDC, that way the idle will drop where it wants, and you can go about with carb, fuel inlet, idle speed, and choke adjustments as necessary.
Any pictures of the bus itself?
_________________
The Bus Barn Ltd. Co.

Oct. ’67 Double Cab (’68 Crew Cab)
[url=http://www.vw-mplate.com/mplate-44412.png]Click to view image[/URL]
March '69 Delivery (Panel Bus)
[url=http://www.vw-mplate.com/mplate-44414.png]Click to view image[/URL]

[SamboSamba22]

Those also look original spark plugs, as is the coil. I had the same ignition coil but replaced it any way, though I have kept it as a back up because it is still good.
May have some voltage drop somewhere along those ignition wires, just food for thought.
_________________
The Bus Barn Ltd. Co.

Oct. ’67 Double Cab (’68 Crew Cab)
[url=http://www.vw-mplate.com/mplate-44412.png]Click to view image[/URL]
March '69 Delivery (Panel Bus)
[url=http://www.vw-mplate.com/mplate-44414.png]Click to view image[/URL]

[restocal63]

Thanks all for your feedback Abscate and SamboSamba22.

A pic of the bus in question

Its a 1975 Kombi with only around I suspect what are original 65000 km only and seems to complete and never messed about. It a work in progress hopefully should be able to complete it by the end of the year.

Ignition leads have been replaced with new ones as well as the plugs. Kept the same extensions from the leads to the plugs though. Replaced a coil with another one from my bugs and still worked the same. My bus only has one vacuum hose connected to the vacuum canister of the distributor.

Shall post further pics of the carbs with the air cleaner removed.

Any other things which I may look at?

Big thanks once again for your precious help.

[Tcash]

First make sure your spark plug wires are on correct.
Find #1 first, it could be in any of the 4 positions on the distributor cap. Do not go by picture.
Follow the #1 spark plug wire to the distributor cap and mark it.
Turn the engine clockwise with the alternator nut, until the rotor points to the #1 spark plug wire on the cap.
Then confirm the rest of the wires are in order.

Next figure out if you have solid or hydraulic lifters? The engine may have had hydraulic cam and lifters put in it at some time. Adjust accordingly.
Lifters Hydraulic or Solid ?

As suggested. Do not mess with your carbs.

[restocal63]

Thanks Tcash for your suggested inputs.

I have rechecked the HT wires from distributor cap to the corresponding cylinders and are as per the below diagrams. Is there a way to check the condenser? I have cranked the engine on all 4 cylinders and obtained a spark from all 4 HT leads and a spark plug earthed although the spark looked weak. Tried also a different coil from one of my bugs but still the same symptoms persist.

However these have been not removed as the engine before these symptoms always ran fine without any misfire or hesitation.

Bus has solid lifters as I suspect that the case has never been opened or messed around given the low mileage of the bus (65000 km). When removing the pushrod tubes for the o-ring replacement, I carefully labelled each item so that it goes back exactly where it was and also adjusted back the valves to 0.15mm(inlet) and 0.2mm (exhaust) respectively.

Have also rechecked these tolerances when the engine was stone cold again.

One thing which I forgot to mention when I now run the bus as in the video is that is smells terribly of gas, am I correct to deduce it is running excessively rich? Could be the exhaust box although new became blocked with the soot and causing excessive back pressure?

I shall not touch the carbs and wait for further suggestions and help but now I am correct to think that air/fuel mixture has been altered in some way, given the way the engine is running? Seems like there is not enough air in the mixture.

Tomorrow shall put in a new set of plugs, just in case they are not performing properly. (When removing them to check them after the fault they where all sooty and not the normal rusty coloured tip.)

As previously mentioned once I had replaced all the vacuum pipes etc. the bus used to start immediately hot or cold even after a week or so. I hope I have a video of the bus running previously before this fault so that one could compare the difference.

Many thanks for your precious help and guidance.

[Tcash]

Bus has solid lifters as I suspect
Do not suspect. Use a flashlight and take a look.
Lifters Hydraulic or Solid ?

Could be the exhaust box although new became blocked with the soot and causing excessive back pressure?
A vacuum test with a vacuum gauge would tell you if the exhaust is restricted.

Type I engine but will give the idea
https://www.youtube.com/watch?v=787INwvir24

Classic VW Beetle BuGs How to Adjust your Valves
https://www.youtube.com/watch?v=T3MgWSXTwWQ
https://www.youtube.com/watch?v=isYX7b5r5Ng

[lil-jinx]

Where do you have the vacuum advance hose connected to the carb.
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1974 Bay Westfalia. she likes to be called Ethel.
1968 Dune Buggy sold dec 2024

1974 parts bus
A smart man learns from his mistakes,a very smart man learns from other's mistakes.

[restocal63]

Found what the problem was

One of the plugs became shorted to ground and caused the entire ignition system to fail and make the engine run very bad.

Now the bus is running back as it was, I wonder what has gone wrong with this NGK as never experienced such thing.....

Thanks to all once again for their time and help.

[Abscate]

Cracked ceramic or defect in metal. The spark plug industry has a pretty difficult problem, making millions of units every year of a product with several failure mechanisms. I've worked on this problem.
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[Tcash]

Thanks for following up. Was that #3?
Tcash

[williamM]

Would you check on the gap?-- sometimes those big backfires can shake some kind of old crap loose and it will briefly bounce around and close the SP gap. I had many Champion plugs dead out of the box while working on outboards in the 80's that cause all kinds of trouble shooting nightmares. Soon learned to test them first before chasing ghosts.
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[restocal63]

Yes Tcash it was the plug for cylinder 3.

Gap was still 0.7mm.

One last question.

Does someone have a picture/part number of the correct or replacement carbon canister to be used for the twin carb setup as mine is missing?

Many thanks all for your help once again.

[williamM]

let me check---[img] This is off my 73-fed emissions.

[/img]

This is the 73

.[img]

[/img]

and don't forget about this buggar- hiding behind the DS tail light and the spare tire bulge--


[img]

[/img]
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some days I get up and just sit and think. Some days I just sit.

opinion untempered by fact is ignorance.

Don't step in any!

[SamboSamba22]

Resto,
That's the charcoal canister you are missing, though location for it in your 74 is just offset of center, along the firewall, more towards the left carb. The large diameter house goes to the port off the shroud as mentioned, the smaller to the vent tubes running along the top of the engine bay.
_________________
The Bus Barn Ltd. Co.

Oct. ’67 Double Cab (’68 Crew Cab)
[url=http://www.vw-mplate.com/mplate-44412.png]Click to view image[/URL]
March '69 Delivery (Panel Bus)
[url=http://www.vw-mplate.com/mplate-44414.png]Click to view image[/URL]

[restocal63]

Once again many thanks to all for your help photos and time.

Made another happy bus owner

Sambosamba22 do you have an exact photo please?

Thanks in advance.