Hi I have a mk2 golf driver 1600 with a weber carb on. Its been a great motor for months but now i have hit a problem............... When the engine is cold with some choke it will start like normal and then idle well, it will drive ok in this state as well. When its warm and the choke is pushed in it now wont pull properly???? This has never been a problem before but yesterday driving back home from work it started spluttering and would not pull in any gear. I pulled over and let the engine cool down for a bit while i checked all vac hoses, leads gaskets and pipes for any leaks or splits but there was none. I then started the engine and it reved freely and i was able to set off again. About 2 miles from home it started loseing power again and i had to coax it home at 20mph. So basicly the car will drive ok cold but as soon as it get hot it will not pull and will cut out yet when hot it will rev freely and tick over fine?????????? Whats going on? i need your help desperatly as i need my car for work. [:^(]
Try rocking the carb from side to side with the engine running to see if the idle changes. The rubber base it sits on may be leaking air, they split with age but are cheap.
Oh, and check that the choke is still operating correctly, get someone to pull the knob while watch the movement.
When it goes into 'dodgy' mode, does re-applying a bit of choke make it better? I'm thinking it's either carb icing (seems slightly unlikely at this time of year, but don't rule it out) or some debris in the idle fuel/air system. If it is the latter it should be improved by pulling a bit of choke back on, 'cos that will bring the main jet into the equation more. If it's carb icing I don't think it'll help much*. Check the warm-air feed system (assuming you have one) and the little cylindrical heater known as the "part throttle channel heater" (in Pierburg context). Generous squirt of carb cleaner around the top and down the venturis can only be good. If none of this works, await more specific ideas from a "Weber man". Edit: there's one^^^! *Thinking more about this, I'm not sure that'll be true. If it's the idle outlet itself that's getting occluded by icing, then giving it some choke will help. Either way, if putting a bit of choke on does help it run better, I think you'll have proven that the problem is with idle fuel delivery.
hi guys Thanks for your help guys. I have started the car and wobbled the carb and nothing happend which was a relief as i replaced the rubber mounting when i fitted the weber, but you never know.... Its just started to lash it down with rain so i will try the choke ideas when it stops (blumming summer my ****!)
You do have the classic symptoms of carb icing! Believe it or not you could have it worse in the summer as warm air holds more water vapour than cooler air. Though it is rare in summer and I have only had it at around 5degrees C. It happened to me the winter before last and I couldnt believe it, last happened 30 years ago on a Viva!! Changed the little heater on the front of the carb, expensive at 27, but not missed a beat since. As said previously check the whole hot air system through and dont use an aftermarket metal heat tube, the heat is lost in transit, go for the VW one. Also check for volts feeding the carb heater, easily done with a light or avo, should be on with ign on. Best of luck! Simon.
I had a the same symptoms on my GTI, as you can guess it wasn't a carb problem, unfortunatly it was the head gasget on it's way out. Thats not to say that it's not carb related and therefore a simple fix, just wanted to make you aware that there is a slim chance it could be the HG.
right i am back after finding some where out of the rain to work in................ I have checked over every thing you guys have said with the engine cold and compression tested the engine which seemed good on all cylinders. I cleaned the carb and all of its mechanisims and lubed the manual choke cable. I was speaking to a friend yesterday about it and he said when did it happen so i told him i had been on a long run, the engine was warm and as i had just come off a round about it lost power and started loseing power. I told him that you guys said it could be carb icing and he thought that it was very likely but as i had just been round a round about may be the float in the carb had jammed? Well i have just been to the car and started it up with not too much fuss and then let it warm up until the fan kicked in. I then pushed the choke in and let it idle for 10 mins with the fan kicking in and out. I then put the hand brake on and put it in to first and loaded the engine as if it was a hill start. To my utter disbeleif it pulled like a train???? so i tried it in some other gears and then went for a short drive. It seems to of cured its self and i dont know how as yesterday when i tried the same method it died.......... I am worried that i dont know why it cured its self but i am glad its back to being drivable now. If i find out why it lost power i shall up date this thread incase it happens to some body else.
arrrgghhh its back again........... I think its some thing ez-pete mentioned about applying choke when it goes bad. This morning on my way to work it went all crapy and lost power when the engine warmed up so i pulled the chole cable out a little and it seemed to solve the problem.............. So does this mean there is some nasty dirt floating around in the carb or could it be some thing more serious internal to the carb?
What sort of air filter do you have on it jimbo? Standard airbox/filter with warm-air feed from the shroud round the exhaust manifold? You could have some debris in the float chamber that's occasionally getting sucked into and blocking the primary idle jet, but I think icing's more likely, unless you can be certain that the intake air temp's being regulated correctly, and the heater that should have been transferred over from the previous carb is present and working. I don't know how easily the 'lid' comes off a Weber to have a look at the bottom of the float chamber? I know it sounds crazy suggesting carb-icing in mid July, but if you actually feel the temperature of your carb body when the engine's fully up to temperature, it's really surprisingly cold. I tried this yesterday, out of curiosity, right after I'd shut down the engine; I'd guess the (Pierburg) carb body was at around 10-15C*. The atomising/vapourising fuel, plus a constant high-speed airstream cools it very effectively. Hence the need for heaters and control of intake air temp. * Edit: tricky to judge this by feel, 'cos being ali, it conducts the fingertip heat away very well. Edit2: simonh makes some good points above regarding humidity, and heater. I happen to have a spare that I could give you (refurbed) on an exchange basis if that turns out to be at fault.
Lid comes of a weber with a about four screws, but you are meant to replace the paper gasket when it goes back on. I agree with the carb icing theory by the way, its certainly quite humid even when it is sunny. Like pete said, what air box/filter is fitted?
You can try this one if you like, not pretty, but it worked over one winter. Disconnect air trunking, as it enters the square black box, with tubes joining it to carb. Jam open the hot air flap, I drilled a hole and used a large self-tapper. Replace trunking. Disconnect the tube from that flap operating chamber and plug with golf tee or similar.. (Cant remember which hose exactly and away at the moment so cannot check!) If the problem does not return (you will also notice less power and darker exhaust) you have had carb icing! Jamming the flap causes constant carb heating. If the problem stays intermittent you probably have fuel contamination. Got the above tips from this site about 3 years back. It might help isolate the problem. Simon.
I am running the standard air box with a K and N filter element and new VAG heater hosing. I dont think the main problem was carb icing as i could replicate the problem whilst the car was stood still so it has not taken enough air in at a constant pressure for a long enough time to create crab icing ( IE a long drive) but it could of been crab icing that high lighted the problem as it all started after a long drive. But i think i might of solved it now........(fingers crossed) I got my self some crab cleaner and went to town on the crab with it. I absolutely drowned it when the engine was hot and let it soak through all the grunge. I then run the engine up and sprayed more cleaner down the crab whilst opening the throttle. This helped to clear a great big oil/petrol bogey in the crab and it then idled beautifully. I noticed that the breather pipes where a little soft and squiggly and the oil was a bit nasty so i replaced all the pipes and did an oil and filter change. So far so good but i will keep you posted if it changes again :-) I will make a point of checking the oil and cleanliness of the carb from now on!! cheers for all your help.
Dont forget that, if this did work, it may point to fuel contamination!!? Keep well topped-up with quality fuel (the additives package is what you are paying for eg:BP/Shell/Esso NOT Tesco!!), change the fuel filter, maybe a fuel system cleaner (only 5 and cannot do any harm)? Lets hope! Simon.
