1977 F-100 300 I6 (all stock)

I started the truck and had it running for 15 seconds at the most with the hood open, and when I shut it off, I stuck my head back under the hood and smelled gas. Pretty quickly I saw gas dripping from this part about every three seconds, and then it stopped. This feeds gas to the carburetor, but what exactly is it, and what else do I need to know? It doesn't look expensive or hard to replace. It has a label on it that says D7TE-DA 6807 15J6A, and from what I can tell, that is a carburetor number for the 351.

 

Its the fuel pump, remove it and install a new one.

 

What Joeseph said X2 and the sooner the better. It may also be leaking to the inside and contaminating your crankcase with gas.