fuel problem i dont get it!!!?

hi this is james
fuel cannot get fuel throught to the combustion chamber i have tryed 3 different carburetors and checked for blokeges and there is not any.I also have looked for blokeges in the fuel cap & the fuel line its all good.When i put a few drops of fuel in the combustion chamber it goes for a cupple of seconds. what is going on?
Any segestions much appreciated.
james, June 2005


done
check all gaskets on carb cannot draw in fuel if it can have air from elsewhere

fixit, June 2005