Ok so my friend has an 04 Blazer and there is a smell of gas coming from upfront. There is some gas residue on this valve looking thing above the alternator. There is a line coming in from the air intake and a line going out that looks like a fuel line. I am just trying to help him out and I am not sure what this part is and if I should help him replace it or not or why its leaking in the first place.