rough engine shutoff

[captin_urbis]

so when i turn off my car, (1.6 carb) its very rough, shakes the entire car (like my diesel did with a dodgey rearbox mount) and takes 2/3 seconds to actually shut off. now im thinking its because its a carb and induction still pulls some fuel through. but im not sure if it actually stops fuel flow or just cuts the electric. would make more sense with what its doing for fuel cut off.

doesnt do it all the time btw.

anyone know what im talking about? any help is much appreceated.

[captin_urbis]

this also happenes......http://www.golfgtiforum.co.uk/index.php?topic=174733.10

[bmotormad]

You think 3secs is bad my syncro(1.8 carb) goes on for over 60 secs, have to turn it off put it into gear and stall it 
Think someone put glow plugs in instead of spark plugs
still it wont be in there for much longer

[lemski]

Needs decarbonising. My 1.6 druver use to do it. For some reason if I let it tickover for a few seconds then turned it off it was fine.

[rubjonny]

get engine hot then hold throttle open a bit and trickle water slowly down the carb. dont let it stall. the water vaporises in the cylinder and steam cleans the inside of the engine for you. worked a treat on my old driver

you need to fix the cause of the carbon buildup though, or it'll just happen again. on mine it was coked up due to autochoke failure, which was caused by a blocked coolant channel oring.  if you have a webber carb now then just get the co checked and that should be all you'll need to do.

I also had some over-ruin issues due to my rad fan being bust, which made the engine get a little hot. only happened in the height of summer though, luckily i figured out the problem before i got stuck in traffic for any length of time or it could have been much worse