[i cant drift worth shit]

I looked at an s13 the other day and when i went to start it it wouldn't do anything lol, the guy is just like "the fuck". So i told him if he gets it running i'll buy it but i dont want to buy a car that doesn't run. He calls me today and says that he hooked up an external fuel pump and it started right up. The harness looked like it was in good shape, not cut up. Also checked the fuse and relay. Relay clicks like it's supposed to and fuse is good. The car has been sitting so i'm thinking maybe bad gas killed the pump? But basically my question is that if i buy this thing what else could be wrong other than the pump? Thanks