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1987 polo classico wont idle


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Can someone please help me?

 

yesterday after i started my polo it ran fine till i started to drive and it would not idle. I had to keep starting and rev the engine to make it home.

 

i pulled carbs out and cleaned carbs and changed air filter. No Change!

 

i start it up and it warms up and idles, once i tap gas it just stalls.

 

In the past i had a problem when i was coming to a stop and put car in neutral it would stall after long drive to work. not sure if that was a sign of the same problem just worse now.

 

Can anybody help me please?

 

is it an idle screw problem? etc.......

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  • JohnLJr

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  • dvderlm

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dvderlm

What sort of carbs?

How did you clean them?

What engine size?

 

If it was Pierburg or Weber single carb I'd suggest vacuum leak at rubber base mount, or fuel line full of rusty sludge that pump cannot overcome to provide sufficient fuel to drive.

How clean is the inline fuel filter?.

 

 

 

 

 

 

 

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I know the carb is not the one in the haynes manual. i have the auto choke.

 

the engine size is 1272

 

i used carb cleaner and a lint free rag

 

should i adjust the idle?

 

 

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dvderlm

You need to clear the idle circuit. Then reset idle mixture. 

 

if car will run with you standing at engine you can use engine suction to clear passages. Hold hand over top of carb (air filter off)

and rev for 3 seconds so hand sucked on. It's 50 vacuum cleaners pulling fuel not air.

 

Compressed air is an alternative. Bike pump, keyboard cleaner  spay.

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dvderlm
6 minutes ago, JohnLJr said:

the inline fuel filter looks clean

That's good news. Rusty tank is ruled out.

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it only idles when cold, once its warm and i tap gas it dies and from there on i cannot run car without reving engine

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this car has been in a garage most of its life, only has 99k kms on it. i dont understand about reseting idle circuit.and idle mixture

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dvderlm

I can't help very well unless you can tell me which carb... or send a photo?

 

I want you to blow air through the very thin passageways that carry air and fuel, but to do this right means removing idle mixture screw, and refitting it afterwards. 

Procedure is a bit different, location of mixture screw is always very low on downdraught carb.

 

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OK I will send a photo tomorrow morning because it’s too dark right now . And I will start from there . Thank you for helping me and talk to you tomorrow 

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dvderlm

Glad to help. I missed your question back in September last year. 
So have you had this problem for nearly 6 months?

 

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When I came to a stop after a long drive to work and the car is up to temp and put car in neutral it would stall . That happened once and a while.

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But now I can’t idle at all done yesterday , I drove it to work the last 4 days. Before then it was sitting for two months due to working over seas

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I took a photo but won’t upload on to the page. I will look up the carbs on google and let you know what kind they are

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dvderlm

I'd expect twin-choke Pierburg 2e3 on a 1272cc. The Haynes chapter 12 supplement for Polo 1982 to 1990 should cover it (yes page 200), but Ruddies Berlin is best source of info.

 

When you tap the gas pedal you are disengaging the fast idle cam at the carb throttle lever.  It might just need a small tweak clockwise.  to the idle speed screw

 

Pierburgs have a plastic pulldown unit that opens the choke flap from fully closed a fraction. This can wear.

Autochoke tben moves choke flap from nearly closed as engine coolant warms.

Is the choke flap fully opened after driving 10 mins?

it might be seized or stiff.

 

Doubt it is the pulldown unit, but if the diaphragm of tbe unit is split the fractional open at first fire does not happen, and worse you get a vacuum leak via the tube operating the pulldown

at the worst place for good idle. Does the choke flap move when engine cold and started?

 

Also check all the other rubber vacuum lines are in good condition.

 

So clearing the idle circuit. Locate the pilot (combined idle airfuel ) jet (smallest, brass,  top of carb), unscrew with correct fitting screwdriver, hold up to light, clean with air.

Use compressed air to blow down the idle circuit hole. It should bubble in the float well.

Refit pilot jet.

 

That might be enough.

 

If not screw idle mixture screw in clockwise gently counting turns (back of carb down plastic tube, very low).

Make note of how many half-turns.

Remove idle mixture screw anticlockwise. (you may break the tube doing this, maybe easier off car, it just helps guide a screwdriver).

Blow compressed air in so it bubbles.

Refit mixture screw all the way in and then turn half-turns anticlockwise to reset to same point.

You may need new rubber o-ring for mixture screw.

 

Finally set for smoothest running (ideally highest vacuum or Bunsen blue flame using Colortune/exhaust gas meter).

 

 

 

 

Edited by dvderlm
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Wow thanks

 

so when I drove the car around yesterday , had to keep reving it would stall, I pulled in my driveway open the hood and the flap was open, when it’s cold engine it’s closed . I will take the carb off and try the idle screw . I will let you know the outcome

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SO I tried to turn idle crew clockwise but it was bottomed out, I took it out , rubber o ring does not look bad, so you know how many turns out it is suppose to be, you think from vibration it turnt in?

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So I adjusted the screw 3 full turns out (6 half turns) same thing , dies after warm and flap is open when warm , I took fuel filter off , there is some dirt inside but I don’t think that would be an idle problem but I will go to store Tuesday and get a new one, also I will be replacing the hoses for the fuel lines which look to have cracks. And I will go from there. I need a beer!

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ok so went back out and started it, while it was warming up i sprayed carb cleaner at the flange between carb and manifold. the idle went down alittle bit. you think that is the problem? what is a good place to order the flange?

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dvderlm

(written while you replied)

Very unlikely for vibration to move it.

The rubber stops rotation.

 

I remembered wrong. Screw down plastic  tube is idle speed screw.

Mixture (CO) screw is at base and has the o-ring.

 

If mixture screw was at bottom, then you must be running and trying to idle on progression holes and part-throttle circuit.

The throttle flap primary should be virtually closed (very thin piece of paper will just fit) at idle. 

 

So  choke flap  is moving well. And a little from closed when engine cold and start? 

Did you check vacuum hoses? There's one to. thermo-valve for hot air flap and perhaps one to distributor advance mechanism and the pulldown unit I mentioned.

Can you increase idle speed using the speed screw?

Or throttle cable clip, just enough to use carb cleaner to spray around hoses and base and listen for engine noise change.

 

Did you blow air to clear any partial blockages?

 

I think my Pierburg needed 1.5 turns out on mixture screw but each engine is a bit different and it is 12 years since I used a Pierburg.

 

 

The base mount can also have a small air leak that is hard to tell.

 

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dvderlm
15 minutes ago, JohnLJr said:

t is a good place to order the flange?

Anywhere that supplies Febi or BirthSPA.

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