Firstly, welcome to the site.
Just disconnect the fuel hose that goes from the pump to the carby at the carby end.
Have a mate crank the car over and see if petrol comes out of the hose.
Be very careful though and make sure you use a bucket or something so you don't spill the petrol on the engine or set it alight.
This will tell you where the problem lies. I.e. if petrol comes out it will be the carby set up.
Good luck
Matt