Check / replace fuel filter but most likely you'll need to pull carburetor and clean / rebuild it. Do yourself and get a rebuild kit that includes parts for fuel pump. It will save you a lot of grief trying to save gaskets and often the diaphragm is stretched a little not letting it work properly.
To get proper kit you'll need to look at front of carb and see if there are 3 or 4 bolts going though the fuel pump body as they require different kits. If you don't feel comfortable doing it yourself then take it to a shop.
I have the kits available on my website if you want to do it yourself. They really aren't that hard to do. Just lay everything out in a clean work place and pay attention how it comes apart.
A couple of quick and cheap things you can try - there will be a hex head cap on the carb at the lower right hand side, remove it, let gas and crap drain out, shot some carb cleaner straight into the main jet located behind that cap. Check the vacuum impulse hose coming from the engine block to the bottom of the fuel pump for cracks, leaks.