Club 80-90 Forums

my mate has an 86 t3 van,(1.9 petrol) its just been to a local mechanic to have tuning done but he carnt set the carb up, he says the c.o. is irratic, and there is a flat spot, can anyone shed any light on this? is it fixable or is it a new carb time?

It could be an air leak into the carb or manifold.
A flat spot can be caused by a knackered rotor arm

Do you really know it's the carb? Is the air intake and filter ok? fuel lines and filters clear? vacuum pipes intact and connected to the rigth places? timing right-dsitributor, leads and plugs ok?

Most people I've encountered with a t25 say there's an inherent flatspot and I have to agree with that; it's just a question of minimising it, unless you go for specialist carbs.

I've only got experience of the pierburg 2e3 but if all the above are ok the flat spot might arise from a damaged accelerator pump diaphragm or inadequate travel on same. Erratic CO, from my limited knowledge suggests inconsistent fuel delivery. If all the above (timing etc ) are good, then it may be worth just stripping and cleaning the carb and checking that the various diaphragms, jets and ports are all clean and and in tact.

I really struggled to find out about with my carb, everybody wrote it off
but once I found a source for parts and changd a cople a pieces, it's been as good as new.

I think I've mentioned it before in the forums but a common source of trouble is the throttle flap. It simply wears out (or at least the bushes at each end through which it runs do). Wear here causes air leaks and makes idling/mixture erratic. The Beetle carb would also get this way, often resulting in the car dying when pulling up at a junction etc.

There is a guy in Clacton, (R Ball, Totlands Drive) who you should be able to locate via the UK Phone Book for his number. Roger rebushes carbs amongst other things by fitting new phosphor bronze ones, although you may well find a skilled lathe man locally who could do it.

An easy way to check for this this prob is to spray WD40 around the flap ends on the outside of the carb when the engine is running (the lower flap not the choke flap). If it suddenly starts to pick up speed - theres your answer - worn bushes. The same basic test can be done with inlet ports too - a spray round the basic joints will sometimes reveal a leak:) The WD40 (or similar stuff from £1 shops) temporarily plugs the gaps and the rise in engine note denotes the origins of the leak/leaks.

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Incidently, my local £1 shop was recently stocking complete wiper blades (the magic multi-wipe variety). Always worth exploring these places from time to time!