Skoda Favorit Pierburg Puzzle

[RicardoM]

Well... that might be a problem

I wonder who put that screw in there and why...

I wonder what other parts might had been replaced too. Looks like the previous owner was quite an 'innovator'...

[PedigreePaul]

Since the last post I've been busy moving to a new house with a garage

 

After last time it still ran rough and had massive fuel consumption. I've replaced the enrichment valve and the accelerator diaphragm. They were stiff and punctured and didn't do anything. I've refurbished the gaskets and mounted the assembly it back on.

Before running I did a smoke test like the one above. There was only smoke coming out on top of the choke plate pot when the choke plate was slightly open, none around the bottom rubber gasket or somewhere else.

 

After I fired up the engine it ran very smooth, no difference in rpms or erratic idling. When I pulled the plug on the idle shutoff valve it stalled, so I guess I solved the vacuum part.

 

I noticed though that when I press and release the throttle the engine still dies.. Let's see if I can fix that

[RicardoM]

I noticed though that when I press and release the throttle the engine still dies.. Let's see if I can fix that

That indicates one of the following issues:

• incorrect mixture (too lean)
• incorrect ignition timing / distributor vacuum diaphragm punctured or plunger stuck
• leaking pulldown diaphragm

[PedigreePaul]

The pulldown unit is holding it's vacuum. Also is the distributor vacuum Diaphragm.

 

I just started the Fav again with the air filter off and it idled good. I removed the distributer hose and air filter hose and plugged it with my thumb, both were sucking vacuum. At 1 certain point (don't know whether my thumb was on or off the hose ends) the revvs went up. Even pulling the plug on the idle cutout did not stall the engine. I stopped it by turning off the key

I started the Fav again: perfect idle and when revving, no stalling at all, only after pulling the plug on the cutout. Still some sorting out to do for the next days

[RicardoM]

OK, keep us posted.

Did you check for correct ignition timing with a strobe timing lamp? Because with a carburetor holding vacuum and perfectly tuned, good air, correct valve timing, and good compression, it's only the ignition timing left to check. Timing at idle, vacuum and centrifugal advance curves. Hook a vacuum gauge in the process as shown. Make a video if possible.

[PedigreePaul]

I did not check it lately, I don't own a strobe light or vacuum gauge.. I don;t see how that does affect the throttle behavior?

 

I did make a video at idle and when I press and release the throttle.

 

https://www.youtube.com/embed/rew7z12Qcx4

Edited 26 March, 2016 by PedigreePaul

[RicardoM]

I thought that when you let go the throttle the engine drops rpm, stumbles a bit then return to idle.

But stalling so easy... as if the shutoff valve is released... that is a new one.

 

What happens if you screw in the misture screw? Drops rpm, stumbles then finally dies?

I had a weird one when the owner replaced the cardboard gasket between upper and lower bodies of the carburetor. He forgot to check if all the holes in the gasket are clear. One of them (the idle channel stage 1 hole in photo) was partially die cut...

 

[PedigreePaul]

I will check that. When reassembling the bodies I did check for matching holes, but I might have missed that small one.

 

Funny thing is, the last time I actuated the throttle it did react normal. I'll try it again and take some new pictures/video's of the current behavior.

I will change one of the vacuum hoses (1 year old but PVC instead of rubber, but might be stiffened since last year, connected the distributor vacuum unit). The rest is fresh and made of rubber

[RicardoM]

Dirt, debris, etc. could do funny things too.

 

[faraj4]

hi Ricardo 

good news : no more black smoke in the exauhst 

bad news : mixture screw all the way in ( blocking mixture ) , and the engine still running . 

car is running smoothly powerfully .

could it be the vaccum unit in the distributor ????

[RicardoM]

Did you change the enrichment valve with a new one? A leaking valve could keep the engine running at idle with mixture screw all in or shutoff valve disconnected.

 

I told you to check the vacuum using smoke. Do it and you will find where is the vacuum leak.

[faraj4]

yes i did change the enrichment valve with a new one . and i checked the vaccum using smoke : the only place was leaking smoke is the axe of the throttle valve 

note : if i turn the idle screw all the way out the engine stops running , and if i turn the choke flap to block air passage the engine also stops running , and if i take the electric cable out of the cutoff valve also the engine stops runing .

yesterday i had a look inside the stage 1 while the engine is running , i could see the throttle valve flooded with fuel but i couldn't locate where the fuel comes from .

i checked vaccum unit of the distributor , it's keeping pressure . i also took out the hose of servo and blocked it's hole in minifold , tried the mixture screw , still the same problem .

i'm really tired of this car . and i do not know what to do . i cannot find new carburator . my carburator is piece of s*** . i think selling the car is my only chance now.

Edited 28 March, 2016 by faraj4

[RicardoM]

i'm really tired of this car . and i do not know what to do . i cannot find new carburator . my carburator is piece of s*** . i think selling the car is my only chance now.

If I remember correctly, the previous owner of the car might had made modifications to the carburetor probably trying to squeeze more power from the engine. In that case, you have only a few options left. If you've lost your patience, sell the car. If you want to dig further why the 1st stage is flooded, there are only few options left. Remember that I gave you the best service manual for the carburetor.

 

Check:

if main fuel jets have the correct diameter or you didn't swap them by mistake

if the float level is correct (loat has the correct weight, it is not punctured, and the float needle valve has the correct length - Pierburg repair kits have a shorter one!!)

if the air/fuel jet was modified or it is broken

if the rubber valve inside accelerator pump is intact

[faraj4]

Hi Ricardo

At last i found one problem : idle fuel air jet is faulty ( the on in the photo ) . the narrow tube is long , it should be short . replaced it with new one with a shorter narrow tube . now when i turn mixture screw all the way in , engine doesnt stop running , but it runs in low rpm . at least i can set mixture screw very much better than before .

Now there is another problem : when the engine is cold , i start the engine , choke rises rpm very good , after a minute or two engine suddenly stops running , i try more than 10 time after that to start engine , then it runs , some times i press fuel pedal the engine stops running . when engine gets a little bit worm , everything goes ok , and all problems gone .

Any advice please ????

[RicardoM]

It is hard to give you more advice when the carburettor is a mess and I don't have direct access to it. You should 'thank' the previous owner for the nightmare he left you with. It is quite understandable why your patience is close to an end. My patience is dying very fast too.

 

I witnessed many times the frustration of people having problems with the carburetor on Felicia. Some wanted to drop their car from a cliff. Some wanted to set their car on fire. But after I cleaned the carburetor, set it back to factory settings, and solved the vacuum leaks, the owners wouldn't sell the car for any sum of money. I don't want to sound that I do wonders, everyone can do the repair / setup if they follow the instructions in service manual. I just want you to know that I've seen people going from agony to ecstasy only from this type of carburetor.

 

In your case, things are tougher probably because people are used to swap parts from other cars or 'tune' their engines according to various experts or popular beliefs.

 

In your particular case, hoping the carburetor has now all its correct parts (!), my only guess is there are still vacuum leaks. I base my diagnostic on your observation that the engine doesn't stop with mixture screw all the way in.

[PedigreePaul]

After the last hickup I started the Fact several times in a row. When revving the throttle there's no more stalling.

Half an hour ago I decided to take it for a test run, in small steps though.

First time and down the driveway, then several meteres up and down the street.It ran good (as far as I can tell). Drove a big round the block, no problems at all

I've made a small video of the car on the driveway, idling. Still sounds like a diesel, but hey, it's not as rough as before

https://m.youtube.com/watch?v=g8fL8gowEeg

[RicardoM]

Good to know you're making progress. But I find more interesting to tell us what was wrong when the engine stalled after a slight acceleration then release.

Edited 5 April, 2016 by RicardoM

[PedigreePaul]

I simply cannot tell. Haven't changed anything since then. Perhaps some blockage in the fuel line?

I ran a few rounds yesterday and the problems hasn't come up again. It is slightly old petrol, so that could be the problem?

Next Saturday I will try it again and keep you updated.

How does it sound to you? Smooth or rough? I can't actually compare the sound with a factory spec Favorit.

[KenONeill]

I simply cannot tell. Haven't changed anything since then. Perhaps some blockage in the fuel line?

I ran a few rounds yesterday and the problems hasn't come up again. It is slightly old petrol, so that could be the problem?

Next Saturday I will try it again and keep you updated.

How does it sound to you? Smooth or rough? I can't actually compare the sound with a factory spec Favorit.

With modern "unleaded" fuels, if the stuff in the tank is over a year old, that could indeed cause problems.

[RicardoM]

How does it sound to you? Smooth or rough? I can't actually compare the sound with a factory spec Favorit.

For a car running on stale fuel, it sounds well. I'm not sure if it's the phone that picks up and enhances high pitch sounds, but it sounds the exhaust system has leaks. Start checking the manifold. Previous videos showing the engine bay sound funny too.

[faraj4]

what could happen if exhaust system has leaks ???

[RicardoM]

In a car that has not an oxygen sensor, if the hole is big enough the only problem is you could poison yourself. Noise too.

[faraj4]

Deleted

Edited 24 May, 2016 by faraj4

[RicardoM]

Although I don't see any photo, I guess you're talking about the fuel vapours separator. Unlike a classic fuel return valve, the separator returns very little fuel to fuel tank but mostly the vapours of fuel. The steel ball acts as a barrier for most of the fuel under pressure but allows the vapours to escape to the tank. In case you are wondering how the separator doesn't blow up from the pressure of the fuel pump... the answer is easy. The fuel pump installed on Felicia and Favorit has a bypass protection. If the output is blocked, the pump will idle.

 

[jms024]

I've uploaded for you the best repair manual for Pierburg 2E3 (Jikov LEKR 28-30). Read it and see if any setting is not as specified.

http://www5.zippyshare.com/v/4bkTdv8f/file.html

 

Hi all. Sorry to pop in this thread but I'm having more or less some common issues with my Felicia. I've replaced the bottom steel and backalite plates with new aftermarket ones but they are now leaking both vacuum and fuel! I will now do as Ricardo instructed; sand them flat and apply silicone rubber gaskets (I could not find Viton sheets).

 

I see there is a manual for these Jikov LEKR 28-30 ... Would be possible to have a copy of it .. it will help me so much in dealing with it. The link previously posted has expired :(