1.3 carb problems!

[bigman_10]

yes before you ask it is the standard auto choke piece-of-sh1t-burg carb. and i'm currently in saving for a weber!

In the meantime the car idles fine when cold but when i've been on a long journy or when the engines up to teperature it has trouble idling. an example is when coming off the motorway and approaching the island if i drop the clutch to change down a gear the revs drop right off to >500 rpm most of the time 300 rpm then it stalls. (i put a rev counter in). also i have noticed a petrol smell and i cant tell where its coming from. i have checked all the fuel lines and in problem areas like the filler cap and where the lines go into the chassis in the engine bay an at the rear. Also it sometimes has trouble putting power down if i put the pedal to the metal some times it hesitates and then kicks in then dies off a bit? I'm not posative but i don't think its carb icing.

I was reading around to try and get info on this and i found on one forum a similar problem and they put it down to vacuum hoses? is this right? would it explain the petrol leak or what about the gasket/seal between manifold and carb this was also mentioned? if so what vacuum hoses are they refering to? any help appreciated

[ben44]

sorry to say it mate but sounds like classic pierburg general sh!tness! (that is a technical term, it says so in the haynes manual )

think rubjonny has a rebuild/tuning guide for the pierburg on the site somewhere!

[ben44]

where are you in the world mate as ive got a fully functional 1.3 pierburg carb you can have for free!cos im nice like that!

[Jay]

For 1.6/1.8 Pierburg Carbs, but might help you a bit
http://www.golfgtiforum.co.uk/index.php?topic=33259.0

[Simeon]

Sounds like it could be carb icing - have you checked the hot air pickup is working?

[bigman_10]

thanks for the link i've breifly read the carb guide before and it is useful but i think the 1.6/1.8 carb is totally different to the 1.05/1.3? i can remeber someone saying this but not sure if its true? yeah it could be carb icing i suppose and that would explain the hesitaion, but how would i check that the hot air pick up is working? i have recently replaced the hot air tube so would that be effecting things, i fitted it properly though and its hardly complicated so i cant imagine i messed anything up? Also what would explain the engine cutting out when up to temp and dropping the clutch i dont think that'd be down to carb icing? i have already increased the idle slightly as i thought it could have been low but it still cuts out? thanks for the replies

[Simeon]

When the engine is cold the choke is on and prevents stalling due to carb icing, but when the engine gets up to temperature choke comes off and carb icing can occur. There should be a flap in the intake pipes, which is vaccum controlled from the carb, that opens and closes to allow the warm air to enter when idling - this flap can seize up so thats probably your next check as you have already replaced the warm air pick up pipe.

[bigman_10]

right ok cheers i'll have a check when my dad brings it back from sainsburys just out of interest how is carb icing caused is it somehting to do with low pressure and the petrol acting as a coolant or something?
thanks again simeon

[Simeon]

Carb icing occurs due to the temperature drop in the venturi causing the water vapour to freeze. The ice forms on the surfaces of the carburetor throat, restricting it. By drawing warm air from around the exhaust manifold when at low revs, the temperature drop doesn't cause freezing so there isn't a problem.

[JMallows]

As Simeon said, check the hot/cold flap. I was told by my garage (VW specialists) that an "official VW mod" is to put something in the flap (like a screw) to hold it open, so that only hot air gets to the carb. I did this, and havent had a problem since, and it doesnt get too hot in the summer either.