Hi pete
its a new needle and seat and diaphrams and no pressure in the tank,i made sure of that. Its a mystery i even disconected the vacume pipe overnight .it must be the head of fuel operating against the resistance of the tension spring some how ,haveing said that i stretched it just as a trial .do you think there is another route fuel could take other than through the needle,i have chucked enough money at it but it is frustrating i can,t get to the bottom of it