i had an issue a while ago with both my carbs leaking fuel. found it to be running far too much fuel pressure and overcoming the float. 
 
today i fitted  pressure regulator and set it to 3.5psi.  the engine was running on 2. so i too the tops off the carbs and found the first carb in line was full of fuel but the second carb was dry.  
 
Is the idea to let the float stop the first one once its filled then prime the second carb?  i guess im just a bit nervouse to let the fuel pump go for a while without starting as i dont want it to leak everywhere again.  
 
pic of my setup.

 
cheers

Hi , maybe the needle and seat is stuck shut and not allowing fuel in. .

The 2 carb fuel supplies are independent from the regulator outlet.  The float and needle of one carb will therefore have nothing to do with the other.  Your plumbing looks like it should so I would expect that what Marty said is correct.  Unscrew the inlets to the carbs and turn over the pump.  If there is fuel coming out of the lines then the issue must be in the carb - either sticky needle valve or maybe you put it all back together wrong!?

Going on the fact that presure is transmitted equaly in liquids then it would not be possible for one carby to have pressure and the other not. In other words, they both should fill up together, unless there was a restriction in the fuel line to the empty carby or the needle and seat is sticking. Cheers,...ron.

Thanks guys. I will check to see if the needle is stuck.

Was as simple as that. Just a stuck needle. Thanks for.the help

Cheers