If your car has been sitting for a long time, you may want to consider cleaning the carburettor. Spray-on carburettor cleaners are good, but if your carburettor has mineral deposits on it, you need to learn how to boil a carburettor. There are two ways to boil a carburettor. Most mechanics immediately jump to the second technique described here, but some mineral deposits will come off using the first bath technique and there will be no need for you to use chemicals.
Heat the distilled water until it is boiling.
Put on the rubber gloves and lower your carburettor into the boiling water. Let sit for ½ hour, maintaining a constant boiling temperature. Remove the carburettor.
Blow the carburettor dry with compressed air, make sure all bolt holes and tube connections are dry. Examine the carburettor, if you see any mineral deposits left, go on to the next step. If the mineral deposits are gone, reinstall your carburettor.
Fill a plastic bottle with 1 gallon of carburettor cleaner of other type of heavy duty chemical tool cleaner. Wearing plastic gloves, submerge the carburettor completely in the cleaner. Wait 20 minutes and remove the carburettor.
Wipe the carburettor dry with a clean rag, when you have dried it as much as possible with a rag, use compressed air to complete the drying. Look to see if the mineral deposits are gone, if they are not, repeat the chemical bath.
Disassemble the carburettor completely as if preparing for a rebuild and boil the parts separately; this way you can get the carburettor as clean as possible.
Do not leave a carburettor in either bath for longer than the times stated or you run the risk of removing the top finish off the metal body, allowing for corrosion.