A Walbro needs to be wired in as it doesnt have an OEM spec harness. Check your connections are good. Did you remember to plug the two sockets back into the top plate of the tank?? Check that they have properly seated...On mine I had to clear a lot of crap out of the top plate to get them back on properly.
Did you remove the fuse to drain the fuel lines before doing the job??Check that you put the fuse back in properly.
If you still have no joy, try taking it back out, disconnecting ALL fuel lines and, in a SAFE place, connect it directly to a battery to see if it is working. If it hasnt worked so far then it wont have any fuel in it so you should be all right. Just use a bit of common sense when dealing with a fuel pump LOL.
Other than that mate, it might be the pump itself thats on the blink.
Good Luck,
TT