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Hi,

 

I own a 1989 Skoda Favorit 1.3 with a Pierburg 2e3, probably the oldest still known to exist in Holland. 

 

The carburettor is being a pain in the you know where/what since the beginning. I can not seem to pin down the problem

 

Issues:

 

- When I start the car, it immediately starts to gallop (going up and down in revs.).

- Driving away:When I press the accelerator paddle lightly, the car bucks and disagrees with me. As soon as the I press down the pedal to full, it goes like the Flash. When I have to slow down (release throttle paddle) in approach of a traffic light or in slow traffic it starts bucking again in low revs. Recently it died with the clutch pressed down, because it was that low on revs. I had to adjust the idle screw to keep it running, although it's still rough

- It runs very rich in idle, even with the mixture screw set low

 

Checked/Replaced

- Vacuum leaks around the mounting flange (none)

- replaced faulty vacuum hoses, mounting flange, distributor cap and rotor, HT leads, spark plugs, air filter (some parts were worn).

- The timing is correct (checked with stroboscope)

- The valve play is correct.

- Choke works like a charm,

- vacuum operated actuators retain vacuum

- part load enrichment valve is operating free 

 

Does anyone recognize these symptoms? Or did i miss something or is it i the electrical part?? Could there be an internal blockage that causes the overfuelling/bucking in idle??

 

I'd appreciate your thoughts

 

with regards,

 

Paul, Holland

 

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How did you check for no vacuum leaks?

Because you describe a 100% certain vacuum leaks situation. Pierburg 2E3 is VERY sensitive to that. A slight leak and you hate your car. A perfect vacuum and you love it.

 

Note: why people constantly forget to tell how the problem started? Let me guess... you cleaned the carb out of the car.

Edited by RicardoM
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The car ran like this when I bought it last April. why did I buy it? It's one of the last 10-15 remaining and it was offered too close to my home to ignore it.

I've checked the base and hoses (replaced with new ones) with brake cleaner. There was no slightest change in revs. I presume an airleak would cause it to run lean rather than rich?

Edited by PedigreePaul
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I've checked the base and hoses (replaced with new ones) with brake cleaner. There was no slightest change in revs. I presume an airleak would cause it to run lean rather than rich?

You will never find vacuum leaks on Pierburg 2E3 (aka Jikov 28-30 LEKR on Favorit and Felicia) with carb cleaner. I cleaned, repaired and set to factory specs dozens of those carbs. All had the same symptoms. All had the same problem: the base gasket not sealing properly. Cooked, warped, etc. you name it.

Edited by RicardoM
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The car ran like this when I bought it last April. why did I buy it? It's one of the last 10-15 remaining and it was offered too close to my home to ignore it.

I've checked the base and hoses (replaced with new ones) with brake cleaner. There was no slightest change in revs. I presume an airleak would cause it to run lean rather than rich?

 

 

You will never find vacuum leaks on Pierburg 2E3 (aka Jikov 28-30 LEKR on Favorit and Felicia) with carb cleaner. I cleaned, repaired and set to factory specs dozens of those carbs. All had the same symptoms. All had the same problem: the base gasket not sealing properly. Cooked, warped, etc. you name it.

The easiest way I've found to check the base gasket (block, heat shield, whatever) for flatness is to put it on a piece of flat window or household mirror glass, and push down on each corner in turn, then turn over and repeat. If it rocks at any time, it's warped and needs replacing.

 

Now wet the glass (film will do), and repeat. Any movement in the water means that the block is bowed and makes contact at the 4 corners but not in mid side.

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I can try that to make sure it's straight. I already out on a new one, as the old one had no rubber left on the bottom and was dried out.. I did slightly lean on the carburettor to see/hear it makes any changes in revving, but it didn't.

 

 

I'll try to make a video tomorrow, so you can hear the engine

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I'll try to make a video tomorrow, so you can hear the engine

When you do that, first remove the air filter housing to expose completely the carburetor.

 

Then start the engine at idle (I expect it to run rough)

 

Screw in the mixture screw all the way.

OR

Unplug the 1-pin connector that feeds the carburetor shutoff valve.

 

If the engine continues to run, there is a vacuum leak. Remember, this carburetor acts weird at slightest vacuum leak. I've seen car owners pulling their hair out and willing to bin their cars from frustration...

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When you do that, first remove the air filter housing to expose completely the carburetor.

 

Then start the engine at idle (I expect it to run rough)

 

Screw in the mixture screw all the way.

OR

Unplug the 1-pin connector that feeds the carburetor shutoff valve.

 

If the engine continues to run, there is a vacuum leak. Remember, this carburetor acts weird at slightest vacuum leak. I've seen car owners pulling their hair out and willing to bin their cars from frustration...

 

I've created a video

 

https://www.youtube.com/watch?v=5VZBIrH_F-o

 

I did as described above. Removed the airfilter, started the engine and pulled the plug on the cutoff eventually. For some more details of the carburettor I've made some additional photographs

 

pre-start situation

20538019412_c6343f1406_z.jpg

20358855660_46ac3267ba_z.jpg

20358856950_f3e535119e_z.jpg

20358858980_2b67a950ff_z.jpg

20358895168_4f522521ca_z.jpg

20538032232_5e833f8446_z.jpg

Edited by PedigreePaul
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Oh yeah... vacuum leak. An engine can't idle with the idle fuel channel blocked by the shutoff valve. Unless it's a vacuum leak.
The carb looks cleaned recently (more or less). It's the usual scenario. The owner wants to clean all that gunk inside carb, takes out  the carb and cleans it on his kitchen table. Nothing wrong so far. But once the carb is removed, the vacuum seal is disturbed around the base gasket. As cooked as it might be, years of driving 'sealed' any gaps with dust, dirt, oil, etc.When installed there is no way that will seal again. The rubber of the gasket looks like stone or like charcoal.
 
So now you know why that happens. You need a new base gasket and some special silicone. I have always used REINZOSIL because it is fuel and heat resistant. Have a close look at all vacuum hoses too. Take one at a time out and bend it to check for cracks.

 

In case you want to know how to really check for vacuum leaks, let me know.

 

NOTE: The engine might need other maintenance operations too to run perfectly. Like setting the ignition advance, checking the distributor, HT leads, spark plugs, etc. But for now the vacuum leak is 90% of the problem. Hopefully the person that cleaned the carb put it back correctly set.

 

PS You'll soon find out that you can only attach 2 Mbytes of photos. Keep that in mind just in case you'll need to attach high resolution photos.

Edited by RicardoM
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Actually, when the carb was off, I have replaced the base gasket with a brand new one... That's the current one.

The HTleads have been replaced and the timing and valve clearance is correct(ed). I'm still boggled about the carburettor running too rich.

A vacuum leak would let more air in, am I right?

For the photos I use my personal Flickr account, so I don't think that's gonna be an issue

Edited by PedigreePaul
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A vacuum leak would let more air in, am I right?

Short theory lesson.

 

Engines on fuel injection

When there is a vacuum leak, unmetered air enters into combustion chamber. The oxygen sensor reports to ECU a lean condition. In turn ECU adds more fuel to keep the stoichiometric air/fuel ratio. The engine will run rich.

 

Engines on carburetor

If the vacuum leak is too big, nothing can make the engine run at idle. There is no ECU to compensate by dumping fuel..

If the vacuum leak is moderate or small, engine starts only with a lot of throttle pumping because to keep it idle only a rich mixture helps. After the engine is 'primed' that way, something else happens naturally. The fuel level in the float chamber gets higher and the engine sucks that excess by Venturi effect. Now the combustion is possible even with idle fuel channel blocked. The engine runs rough, hunts (like in your video) and the consumption is huge (up to 20 l/100km). That is why your engine keeps idling.

 

Now back to your car. You have the disadvantage of not knowing if the carburetor has been set properly. I am referring especially to the correct level of fuel inside float chamber. If too high the carb is flooded, the spark plugs are black / wet, and the exhaust pipe shoots black smoke when the engine is revved.

 

You have to find evidence there is a vacuum leak or somebody installed the wrong float needle valve. Some Pierburg repair kits are good for VW but not for Skoda.

Edited by RicardoM
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Okay, that sounds clear to me. Thanks for explaining.

I'll have to check all the vacuum lines including the vacuum operated items again. I do have a spare base gasket, if the current one needs replacing. More work to do!

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I'm having another idea, relating to rich running.

 

Apart from the correct idle jet size, having the correct float height is critical to making a carb (any carb that uses a float) work correctly. You will get rich running... if the float is leaky and therefore sits too low so you need to check the float very carefully indeed for pinholes, particularly on the lower half.

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Ken, why do you repeat what I have already said??
 

Now back to your car. You have the disadvantage of not knowing if the carburetor has been set properly. I am referring especially to the correct level of fuel inside float chamber. If too high the carb is flooded, the spark plugs are black / wet, and the exhaust pipe shoots black smoke when the engine is revved.

Furthermore I have never seen a punctured float in a 2E carburetor. They are made of special fuel resistant plastic.But I have seen shorter needle valves made tor Pierburg 2E3 fitted to Jikov 28-30 carburetors that equip Favorit and Felicia. From photos that looks to be a Jikov carb (Pierburg made by Czechs).

 

PedigreePaul you will need a lot of patience and determination to fix a vacuum leak around base gasket. It is a pig of a job. New gaskets are far from the quality of factory ones that lasted 20 years.

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  • 4 weeks later...

I just got back from my summer holidays.

 

I started to check all the vacuum parts again and found out the choke pull down was not keeping it's vacuum. When I took it apart:

 

21264405925_7af50a13f6_z.jpg

 

So indeed a big vacuum leak, like you mentioned Ricardo.

 

with regards

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The semi-automatic cold starting mechanism of Pierburg 2E3 (the choke) works well as long as every component is good.

The choke is the mostcomplex device having 4 parts that must work flawlessly.

  1. vacuumatic part - the pulldown device that you have found to be punctured
  2. thermal part - thee biimetallic coil inside the choke housing - driven by the coolant heat
  3. mechanical part - 2 springs, a stepper cam and levers
  4. electrical part - a heater resistance that adds heat to part 2

The pulldown device should open slightly (2 mm) the choke flap during engine warmup. A hole in the diaphragm not only that creates a vacuum leak, but restricts the air intake making the engine run rough, on very rich mixture. As soon as you open the throttle plate, you force opening the choke plate, the engine has enough air to run smoothly and the car accelerates massively.

 

The good news is you found the problem. The bad news is new pulldown capsules are made in China (yeah they have fancy European labels, we know the scam) so I recommend buying two. Some don't hold vacuum from factory :swear:

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  • 5 months later...

I just got back from my summer holidays.

 

I started to check all the vacuum parts again and found out the choke pull down was not keeping it's vacuum. When I took it apart:

 

21264405925_7af50a13f6_z.jpg

 

So indeed a big vacuum leak, like you mentioned Ricardo.

 

with regards

i just want to ask you is this (enrichment valve diaphragm) or (vacuum pull-down) ???? 

because the (vacuum pull-down) could not be deassembled ... am i right ???

Edited by faraj4
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Hi faraj and welcome to the forum.

The photo you have referred to shows indeed the inside diaphragm of the vacuum pulldown unit.

Why do you ask? Do you have problems with one of them?

 

PS

I hope you are far from the war zone. I wish Syrian people strength and courage to defend against all foreign aggressors.

 

HVDbUsQ.jpg

Edited by RicardoM
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Hi faraj and welcome to the forum.

The photo you have referred to shows indeed the inside diaphragm of the vacuum pulldown unit.

Why do you ask? Do you have problems with one of them?

 

PS

I hope you are far from the war zone. I wish Syrian people strength and courage to defend against all foreign aggressors.

 

HVDbUsQ.jpg

hi Ricardo . and thank you for your encouragement , im far from war zone indeed , and Syrian people will defend our Syrian against terrorism 

for my question : actually i have a problem in my carburator , which is that i turn the co mixture screw all the way in ( closed ) and the engine stays running , and i have black smoke and heavy fuel consumption , what i did was the next things :

1- cleaning carburator and changing gaskets  

2- changing jets 

3- new carburator base with new gaskets  

4- new enrichment valve 

5- changed all hoses in the carburator

note : when i close starter flap the engine turns of ....

i have doubt about choke pull down as to leak ... but i dont know how to disassemble it .. thats why i ask about it 

thank you for your help

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Oh yeah, the answer is simple: VACUUM LEAK. The new base gasket is not sealing properly. Any vacuum leak and the carburetor will not work as it should. I've seen the symptoms on countless 2E3 carburetors.

 

What kind of base gasket do you have now? The old type (rubber over steel)? Or the new type (steel plate and plastic spacer) ? Depending on your answer I will tell you what to do.

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Oh yeah, the answer is simple: VACUUM LEAK. The new base gasket is not sealing properly. Any vacuum leak and the carburetor will not work as it should. I've seen the symptoms on countless 2E3 carburetors.

 

What kind of base gasket do you have now? The old type (rubber over steel)? Or the new type (steel plate and plastic spacer) ? Depending on your answer I will tell you what to do.

i have the new steel plate and plastic spacer ...

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