Renault Master 2.2 D 2001?

hi I have a Renault Master 2.2 D, med/wheelbase van 2001. I just found out the braking vacuum pump was clicking so i have taken out the pump to find out it was faulty
so i replaced the pump, Then on testing the braking system on the road you could pump the foot brake one or two times then the brake pedal would go stiff, and you have to put your foot down real hard for the brake to work. the brakes where fine be for i put a new pump on, Can any one help please. Could it be the master Cylinder.