Just got a new petcock from HD store, I got fuel at the petcock, b ut nothing is going through or coming out. Did I do something wrong?

 

Well, are you sucking on the vaccum line? Since the 90's HD has used a vaccum shutoff valve. It won't let fuel through without either you or the engine sucking on the hose that should be connected to it and the manifold/carb

 

I never could get any to work with me sucking so I got a little hand held pump to use after I had 3 defective returns---------but thats me