Series 3 New Webber Carb

I have recently fitted a new Webber Carb to my 2.4 S3 Petrol Land Rover it started and ran well for about 20 minutes then no matter what I did the vehical will not fire, do i need to adjust bthe Carb if i use easy start bthe engine runs for about 1 minute. any advise would be most welcome

you've answered your own question. fuel isnt getting to the cylinders. what did you have before? is the fuel pump working? the the float chamber full or empty?