Club 80-90 Forums

OK
From your video it is clear that the choke pull down unit is NOT performing correctly
When the choke is closed and you rev the engine it should pull the flap open.
This suggests either a lack of vacuum to operate the unit from a leak.. or a poorly adjusted one.
It is also clear that the engine runs quite well when cold.
It is evident that the choke opens correctly but the fast idle was not present.
Once warm, the fuel mixture is not being enriched and the engine falters... weak mixture engines will rev on tickover but under load the power produced from the detonation is useless... finally when the lower rpm is reached the power is not enough to keep the engine turning over.
The accelerator pump will enrich the fuel briefly when the accelerator is operated, allowing the engine to spin up. (this pump is operated by linkages directly from the throttle spindle.)

If the timing was way off.. the engine would simply not start.
But no harm in checking it.
I am convinced this issue is fuel related, because the engine can be spun up on the acc. pump which briefly enriches the mixture.

"kangarooing" is caused by a fuel/air imbalance, usually too much fuel when the acc is pressed on a close to stalling engine.
you get a mix right, mix wrong, mix right, mix wrong, and so on....
My engine lurches slightly, like this at low rpm in second or first, just coasting with traffic.. dipping the clutch allows the engine to pick the rpm up and tick over

Things to check
The anti dieseling valve, you say you heard a click, Now it's time to see if that click is actually opening the valve fully. I suggest you remove and observe.
The choke pull down and associated hose, from the video it appears to not be operating.

I'm pretty sure you now have a better understanding on the pierburgs operation and what does what, with this in mind, fuel delivery to a metering device should be constant, the metering device should be clean and free from foreign bodies. It's operation is a simple affair.

The final thing to check before we abandon fuel/air related issues is the actual mixture at idle
The mixture screw should not be messed with without a gas analyser really, but the analyser would show an air leak so it's not specific enough.
A base setting is 2 1/2 turns out.
screw the adjuster in and COUNT THE TURNS. this will ensure the screw is returned to it's original pos. if this is not the issue.
(the screw is an air screw, not fuel)

once all the fuel/air avenues have been discounted we can move on to other reasons....elimination, with positive affirmatives means you can move on with confidence.
good luck my friend

Hi all, quick update on this issue. I have also got 5 new videos to view. Here we go....

Video 1 - http://youtu.be/o8Yqh_zK0ZU" onclick="window.open(this.href);return false;
I removed the fuel cut off (dieseling valve) this morning and when I turned the ignition on and off three times, nothing happened. This can be seen in the first video. I would just like to note that while trying to video it the first time round the fuel cut off valve slipped off the hose I had rested it on and the end touched some metal on the carb, it made a crackling sound with the ignition engaged. Hope that's not the reason it would now appear broken??? So after the first video I left the ignition on and touched the end of the fuel cut off valve against metal (very briefly) and again it made a crackling sound????

Video 2 - http://youtu.be/OngFIfT99jY" onclick="window.open(this.href);return false;
The second video shows me sucking through the pipe on the choke pull down unit and the effect it has on the choke flap. This video was taken with the engine stone cold, I hadn't even tried to start it. At the end of the video I put my tongue over the pipe and you can see the choke flap is held open until I release it. The choke flap will not open any further with me sucking through the choke pull down and it feels to hit a definite restriction at this point. In video 4 you can hopefully see what I mean by restriction.

Video 3 - http://youtu.be/EgxCOCO5xcU" onclick="window.open(this.href);return false;
In this video I have removed the end of the fuel line which goes into the carb and pointed it into an empty measuring jug. Upon watching this video back I can strongly recommend that this is definitely not the way to do it. A bit of fuel did not hit inside the jug and I am sure if the engine was red hot I probably would have had a fire risk. This was however the first turning off the engine this morning so again, stone cold. My excuse is that I was trying to catch it all on video. The jug had around 25/30ml in. They look like good solid squirts to me???

Video 4 - http://youtu.be/7mGsbr3yhyk" onclick="window.open(this.href);return false;
I did this video to give kevtherev a better idea of my choke pulldown operation without him actually been present. Its a side on view from the right hand side of the carb which shows the lever of the choke pull down in operation. It may be a little tricky to see but that was the best I could get after about 5 takes. I should note that in this video I am just sucking the end of the pipe from the choke pull down unit to make it move.

Video 5 - http://youtu.be/6eQDiPtBmWA" onclick="window.open(this.href);return false;
Not sure if this video is any use to any of you but it shows me manually stepping opening the choke flap from the right hand side of the carb. You can clearly hear the different steps as it opens. A quick flick of the throttle releases it back to its original starting position.

So, I believe the last thing you require me to do kevtherev is adjust the mixture screw??? I haven't touched this yet because I believe I have found at least one fault in the above videos???? Should I order a new fuel cut off valve??? and choke pull down unit???

I have not yet done anything with the dizzy or timing. If I've got to order new parts I will get serviceable items at the same time.

Kevtherev, what are your thoughts on the effect of me removing the vac line from the back of the carb which connects to the distributor diaphragm and that resulting in an instant stall???

OK I have reviewed your videos Ben

1, if the valve doesn't open constantly... it's broke. this must be rectified before proceeding with other tasks.
2. The choke flap works perfectly by mouth, let's see it working by the carb, reconnect and test on a cold engine then rev it...the flap should do what your mouth does (as an aside is the restrictor present in the pull down vac pipe?)
3. Perfect pumping
4. Perfectly adjusted (does the 3mm gap appear when the engine starts?)
5. The step fast idle is linked to the choke flap but operates independently with opposed springs, the bi-metal spring in the spring housing moves the flap. With the engine off, and cold, press the accelerator fully, then look carefully for the cam and note its position

here it is in the cold start position

Thanks Kev,

I will order a new fuel cut off valve. Should the nib on the end about 1cm long be moving completely in and out. I.e. should its movement be obvious because I can't see anything moving in the video??

The video I posted yesterday evening (http://youtu.be/YuH607O3gNQ" onclick="window.open(this.href);return false;) shows the choke flap in operation by the carb from a cold start. When I rev it from cold the choke flap doesn't move any further open than its original starting position (3.3mm) but opens gradually as the engine warms up. The same video also shows the choke flap moving from completely closed to 3mm upon startup. When I am moving the choke flap with my mouth, I am only moving it from completely closed to the 3mm position.

Sorry to sound like a div but with regards to this " The step fast idle is linked to the choke flap but operates independently with opposed springs, the bi-metal spring in the spring housing moves the flap. With the engine off, and cold, press the accelerator fully, then look carefully for the cam and note its position"

I can obviously carry out the depressing of the accelerator fully but would it be possible for you to use some arrows and itentification tags on your picture to highlight exactly what it is im looking for because I am unsure what the cam is and what position I should be noting????

Again for my own personal understanding, would the choke flap open to 3mm from close upon cold start and continue opening gradually while the engine is warming without the choke pull down working??

Thanks again. Feel like I might be stating to get somewhere....

I will order a new fuel cut off valve. Should the nib on the end about 1cm long be moving completely in and out. I.e. should its movement be obvious because I can't see anything moving in the video??

yes very obvious

The video I posted yesterday evening (http://youtu.be/YuH607O3gNQ" onclick="window.open(this.href);return false;) shows the choke flap in operation by the carb from a cold start. When I rev it from cold the choke flap doesn't move any further open than its original starting position (3.3mm) but opens gradually as the engine warms up. The same video also shows the choke flap moving from completely closed to 3mm upon startup. When I am moving the choke flap with my mouth, I am only moving it from completely closed to the 3mm position.

the flap should open and close as you rev and idle , this prevents over fueling under acceleration
it should not stay progressive it should respond to the throttle
the mouth operation was perfect.
Take a look in the Haynes regarding the flap setting

I can obviously carry out the depressing of the accelerator fully but would it be possible for you to use some arrows and itentification tags on your picture to highlight exactly what it is im looking for because I am unsure what the cam is and what position I should be noting????

some pretty pictures here
https://club8090.co.uk/forum/viewtopic.p ... g#p7827464" onclick="window.open(this.href);return false;
the position should be as shown in the picture supplied, with the fast idle adjusting screw on the highest step..the lowest step disengages the fast idle mechanism

Again for my own personal understanding, would the choke flap open to 3mm from close upon cold start and continue opening gradually while the engine is warming without the choke pull down working??

yes

what are your thoughts on the effect of me removing the vac line from the back of the carb which connects to the distributor diaphragm and that resulting in an instant stall???

According to the Haynes you time the DG engine at 5' BTDC with the vacuum advance disconnected. If your van won't run with the vac disconnected I would say the starting point for your timing is wrong. The van should start & idle with the vac advance disconnected. You should be able to open the throttle and the mechanical advance should increase the firing point (more degrees before TDC as the throttle is opened up to about 30' BTDC.) with the vac line disconnected. All the vacuum advance does is add an extra 10-12 degrees of advance at high revs / large throttle openings.

The way your engine stalls when you just open the throttle a small amount is like the vac signal is coming in too soon, advancing the timing from 5' to 17' BTDC before the revs have had chance to increase. If this is what's happening the spark fires early and the piston is stalled on its way to TDC.

this is a really insightful thread, even though i havent got a Pierburg carb, excellent stuff

Quick update....

Well I have realised why the fuel cut off solenoid didn't move in my video...Because I didn't have it grounded!!! So, I have re-tested the solenoid with it grounded and the little nib inside the tip of the solenoid moves backwards and holds there until the ignition is disengaged. Now, the only issue I had was that it didn't look like the little nib/pin moved back far enough to completely free the four little holes that run around the circumference of the solenoid which is where I assume the fuel runs through??? With that in mind I have taken two photos of the solenoid. The first with the nib closed and the second with the nib open. This was held open by me manually because I couldn't get a photo of this clearly enough on the camper. I can assure everyone though that the nib inside the tip of the solenoid does move backwards and forwards as the ignition is engaged and disengaged.

What I really need is for one of you guys to remove your fuel cut off solenoid and tell me if my nib is moving back as far as it should????

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Back to the choke flap now. Am I right in thinking then Kev that the choke flap should be snapping open when im revving it while the choke is still in operation and closing when I release the throttle, but once its warmed up it should remain in the fully vertical position no matter what throttle response I give???

I know for sure that the choke flap doesn't move under throttle so what is causing this problem and how do I rectify it???

Also, thanks for the novice guide on the cam and I now understand that I need to see which notch of the cam it is resting on once the accelerator has been depressed fully from cold. I will report back with my finding on this tomorrow.

Oh, and I loved the hairdryer video showing the spring unwinding. Now I also understand why the choke flap opens. This is proving to be a real learning experience.

Hi Boxy,

I don't know anyone with a timing light to check the timing but your explanations are definitely helping me understand the dizzy vacuum more. Once I have sorted this choke/carb issue I will be getting the timing checked. It's just that I can't take the van to a garage to get this done at the minute because it just stalls and kangaroos after its warmed up. Do you have a link to a video of the timing been done on a T25 1.9DG??

Hi Everyone, I thought I would give you all an update as to the stalling/kangarooing issue with my T25.

Well I can start by saying it's FIXED!!!!!.......Touch wood.

We have done nearly 200 trouble free miles and the van has ran beautifully throughout.

The problem was related to a few issues which were very simple fixes. Firstly, it looks like the problem stemmed from me inadvertently running the fuel down too low and then driving up a very steep dual carriageway pulling crap through the fuel system and into the carb plus the obvious build up of deposits over the years.

I had the carb off twice and cleaned everywhere I could with carb cleaner, squirting it through the jets etc and putting it all back together. I cleaned the little cone filter which had heavy build up, replaced fuel lines, fuel pump, the in-line fuel filter but still the van wouldn't idle. I would have bet money on the fact it wasn't related to fuel. After months of fettling around and changing different parts I gave in and spoke to a local garage that gave me the number of a mobile mechanic who used to own the carburettor centre in Halifax, West Yorkshire, His name is Tim. He is semi retired now and when I spoke to him I knew straight away that he knew exactly what he was talking about. He knows carbs and the Pierburg 2E3 inside out. I arranged for him to come out to my house to look at the van.

When he arrived we started it up and he had a listen etc to what was going on. He whipped the carb off in about 20 seconds and went straight for the idle jet. He did something which I never did and have now realised my simple mistake. He undid the gold (i think) coloured idle jet screw cap and actually removed the jet (i didn't know you could do this, silly i know). Sure enough, it had a tiny blockage which didn't stop carb cleaner going through when I squirted it straight through the screw cap without removing the jet (i hope this is making sense). While he had the carb apart and was looking in the float bowl he also noticed a very small amount of water in the fuel. Oh dear, not good!!!

Again this is something I am ashamed to admit but will do incase it helps anyone else out. The water is at the bottom of the float bowl not the top. When I had previously checked for water I had been scanning the top thinking the water would float but it actually weighs more than the fuel and is situated at the bottom if you have any. We checked the in-line filter near the tank and there wasn't any water in that so without wishing to remove the fuel tank for now we decided to carry on. Tim said that it would be best to drain the tank out to remove the water and clean out any debris but I don't fancy that big job just yet so he also said that i could try some specialist fuel system conditioner which removes water from the tank, cleans the carb etc. More on this later.....

Anyway, Tim put the carb back together and re-fitted to the manifold. We turned the van over a couple of times and she fired up and idled. It was pretty ropey as I had been messing with the idle speed screw and fuel/air mixture during my fettling period. Tim adjusted the mixture screw and idle speed screw repeating the process to achieve an optimum idle. He also noticed that the accelerator linkage which operates the accelerator diaphragm on the front of the carb when I press the accelerator was not in immediate contact so I had a small flat spot at the beginning of my rev range. Basically, when i pressed the accelerator the carb would begin to rev but no fuel was been squirted by the diaphragm on the front of the carb. The linkage is at the bottom left hand side of the carb as you look at it from the rear of your van. Tim adjusted this to remove the flat spot.

At this point the van was sounding better than I had ever heard it. He then set about checking the timing. Upon checking the timing he discovered it was out by 4 degrees (i think it was 4 anyway). He adjusted it (with the vacumm advance off) and tried explaining to me how to check it etc and what the readings were for no advance, with advance and full revs. It all went a little over my head to be honest but I couldn't belive how good it was now running.

After Tim had finished setting the carb and timing up on the van we took it out for a test drive. Tim followed me in his van with all his tools etc in case anything didn't quite go right but it went swimmingly. I drove around 2 miles with the biggest smile on my face. I had spent 6 months doing the restoration only to discover I had running issues which weren't present when I bought it. The then 3 plus months of fettling around and pulling hair out had drove me to the end so to finally get it up and running has been amazing.

So, after we got back to my house following the little test drive we had a chat about camping etc as Tim also has a motorhome (not vw) I asked him how much it would be for the work. He said £30!!!! I was delighted. I gave him £40, he might have only been there an hour and a half but I would have been happy paying many more times that to finally get the van fixed. Tim's knowledge and experience in working with these carbs really showed and I only wish I had contacted him sooner. Three months of messing around on and off nearly drove me to the end.

Finally, after Tim left I went and purchased some fuel sytem cleaner. I used the DAE fuel system conditioner which actually says on it that it removes water from the fuel tank. This came with some "professional use only" instructions and I followed them as instructed. I am not advising others to try this just stating what I did. I will use this as part of a regular maintaneance cycle, inserting it into my fuel tank at the quater full mark (as instructed) to hopefully remove any water from the fuel system. I haven't had any water in fuel related issues as yet. As for where the water came from, Well, during the restoration I noticed a few splits and holes in the rubber fuel filler neck which would be allowing water into the fuel system if it had been driven in the rain. The rain would be flying up from the wheels and dropping down into the fuel tank. i know its common for the tanks on the T25 to corrode on the top but I dont think my tank has correded all the way through on the top as i can fill it up with no smell of petrol or any leaking petrol.

So, there you have it. I really hope this thread helps a few people out and if anyone in the yorkshire region wants Tim's number then send me a message and I will give it to you. The van now runs so smooth and we have enjoyed two trips to the Yorkshire Dales.

Happy Camping Everyone.

Amazingly helpful post!! Thanks for taking the time. Now go and it enjoy driving her!!

Found this interesting article on our problems
http://www.members.shaw.ca/bilbo/WBafm.html" onclick="window.open(this.href);return false;