Spent the weekend fitting a brand new weber carb. Everything went well, and when I took the car out sunday it ran like a dream. However, came to start it monday, pulled the choke right out as usual and when I pulled away it was hesitating and stuttering and kept cutting out. It was also choked up when I restarted it and needed a good blip of the throttle to clear its lungs. This happened about 5 times in the space of a mile of town driving at junctions etc. Not sure why it's doing this. Any weber gurus have any advice?
take the airbox off and check that the manual choke flap is operating correctly, is my first suggestion
Nr1 thing to do after fitting a Weber DMTL is go to a garage and pay for a carb tune up. The Weber instructions should be regarded as a guide to get you running well enough to get to a man with a gas analyser. Check the choke operation like Chopperoli suggests, the flap should be vertical with the choke pushed in and completley closed with the choke pulled out, and of course a smooth operator inbetween. I had a problem in the past with the choke snapping to open (off) under acceleration, so you need to make sure that the choke is holding its position at all the various openings until the engine is warm enough to run with no choke.
Thanks mate. Literally booked it in this morning for monday. Full engine tune at a carb and injection specialist. Hopefully this will get it running right. I think it's running too rich.
In the meantime, and assuming that choke cable function appears to be completely OK, you could try leaning the idle mixture with the CO adjustment screw. Strange that it was OK one day and then not the next though . Are you still using the factory airbox (highly recommended)?
Factory airbox, and all factory piping etc. It was warm sunday and really cold and wet yesterday evening when the problems occured. I do seem to have a problem with the choke cable which I think could be to blame also.
Also, there is a loud hissing noise from the carb. I sort of thought it was the way they sounded but i'm not 100%.
Hissing?? Thats not right, sounds like a vacuum hose isn't connected or blocked off. Make sure its connected like this diagram, any unused vacuum outlets need to blocked off.
pooey bum bums. I think this is causing the hissing. I haven't got the vacuum pipe from the rear of the carb to the airbox. It's in a box in the shed! Better put that on tonight. Could this be causing my problems?
Quite possibly, but it sounded like you found a problem with the choke cable too? When you've reconnected that pipe to the airbox thermostat, check that you are getting suction through the thermostat too, towards the diaphragm which controls the warm/cool air flap. With cold engine, just started, you should feel a reasonable 'suck' here (i.e. from the other nipple). If not the thermostat may be clogged up internally. You may be able to fix this by attaching a vac hose to each 'nipple' (in turn) and blowing into it. Then obviously return all hoses to the correct layout. Replacement thermostat is about 30 so well worth a go! I just had to re-do mine like this (successfully) as my in-car display of airbox air temp was telling me all was not well. The reason they get clogged is that there's a ball-bearing valve into the airbox, which opens whenever the air temp is over 20C, drawing air through the thermostat from inside the airbox (and so sucking less/not-at-all on the diaphragm). Although on the 'clean' side of the air filter, this air will be contaminated with tiny oil droplets from the rocker cover breather. You may see evidence of this oil in the hose that goes to the back of the carb, if it's the transparent type.
Thanks maximo, (and everyone else!). Haven't used club gti for years, forgot how many knowledgeable people resided here!
Indeed Pete. Have another choke cable now to put on now so should be allowing full trvael of the choke flap.
Also make sure that the warm air flap has not seized too. If it has, the thermostat will not be able to control the warm air (obviously ).
