Hi guys attached hopefully 2 photos from my carb. On a cold start it runs fine with the vent closed. The problem is it stools after a few mins and the vent is open fully allowing an incorrect air to fuel ratio, so I believe. Is this the problem and how do I fix it. Many thanks

When you say vent, are you refering to the choke flap? This should be fully open when choke is off (engine 'warm').

When choke is active, idle speed will be high enough to conceal a poblem with the anti-stall device.

Please post model of carb - or photo with air filter housing removed. Different carb types have different ways of maintaining idle speed. May just be a vacuum hose adrift.

Its a Pierburg carb will check model tomorrow as I didn't write it down. Its a 1989 Polo Ranger. Thanks for your reply

Don't make any adjustments until you have checked for vacuum leaks (as mentioned above) this includes the carb base mounting which is rubber - no need to remove carb to check it, but, when the engine is warm and it is idling OK, try grasping hold of the carb and moving it about on its mounting - if the engine speeds up or slows down, the mounting probably needs replacing.

On the off side of the carb, you will see a black plastic dome, held in place with three screws, this is the choke adjustment.

If there aren't any vacuum leaks, try slackening off ( don't remove) these three screws and turn the plastic dome very slightly towards the '+' mark on the edge of it, tighten the screws and leave the engine to go cold (overnight is best).

Before you start the engine from cold, press the accelerator pedal down once only.

Start the engine - if it now stays on choke long enough to maintain a steady idle, then you have got the adjustment spot on.

If it still gives you the same problem, again leave it to go cold and repeat the above.

If the choke refuses to go 'off' and the engine runs rich after it has warmed up, then you have turned the plastic cap too far and need to reverse the above procedure by turning the cap towards the '-' mark.

Regards

The car idles fine cold, stools when warmed up after 2-3 mins. Thanks for advice will check tomorrow

Take off the air cleaner cover and check that the choke is going 'off' (opening) when the engine is hot.

2-3 minutes is not a lot of time for it to get hot though, so it could still be that the choke is opening too early - If it is opening within that time, the adjustment probably needs turning slightly towards the '+' mark.

Regards

Dont know if your still looking at this problem or if you have resolved it?

I've not been around for the last few days.

Pierburg;

Look at the front drivers side of the carb and you should see the idler adjuster.

Coming from the idle adjuster (pointing towards the passenger side) should be a vacuum hose.

This vacuum hose attaches to a electronic valve (passenger side of the valve).

The electronic valve (drivers side of valve) connects to one of the pair of vacuum connections on the back of the carb.

The electronic connections of the valve are fed from the coil feed so that when the idle drops, the valve opens, allowing vacuum to operate the idler adjuster on the carb.

As CP says, the carb mount splitting is a very common problem with these. Either rock the carb gently and listen for the idle changing or spray a little easystart/brake cleaner near the carb base and see if revs increase. Remember - just to spray a little, both these products flash really well and will cost you your eyebrows if you use too much.

If you do need a carb mount - avoid the GSF primates in favour of allPartsZone, about a quarter of the price. Not that allPartsZone don't also talk through their primary orafice (just less often), are not afraid of admitting a mistake, will not trot out the same tired old excuses, do not expect to be worshiped and fling less excrement (there may be one or two there who could almost qualify as human - something GSF can only dream of).

Good luck and let us know how you get on.

Yeah, it's crazy how quickly the rubber flange mounting can perish too.

Replaced my flange when I got the car, ran much better. Within 18 months I had to replace it again.

As it perishes it tends to have more play to it, the carb should be fairly rigid when mounted on the inlet manifold. Mine was wobbling all over the show.

It's worth noting that you may not hear any air leaks coming from it, I didn't and mine was completely buggered (with two giant slits running up the sides).

If checking the flange doesn't cure it, it could be your mixture. I bought the Gunson Colortune kit from Amazon. Real easy to use and worked wonders.

Other people have also had issues with the carb on idle when it isn't getting the full 12v from the battery.

Alex

Edited 22 September, 201510 yr by herrdavies

On 04/08/2015 at 13:53, kbs said:

Look at the front drivers side of the carb and you should see the idler adjuster.

Coming from the idle adjuster (pointing towards the passenger side) should be a vacuum hose.

This vacuum hose attaches to a electronic valve (passenger side of the valve).

The electronic valve (drivers side of valve) connects to one of the pair of vacuum connections on the back of the carb.

The electronic connections of the valve are fed from the coil feed so that when the idle drops, the valve opens, allowing vacuum to operate the idler adjuster on the carb.

 

What's the best way to test these idle boost valves? Are replacements or equivalent replacement units available?

Thanks,

Rich.

Pretty sure that system is only used on the Pierburg 2e4 as used in T25 van with 1.9 litre engine.

 

Polo 1.3 1982 to 1989 would have a twin choke 2e3 carb.

 

Manuals for both (and Solex PICT 34 single choke) here

https://syncrosport.com/info/manual/

Edited 4 October, 20241 yr by dvderlm