I found this line coming out of my fuel pump and the hose it's connected to is messed up. I need to know what it's for and how to replace it.

 

I meant coming out of my tank to this black box

 

Uh, cut it off, measure how big the fittings are, go get a couple inches of that size hose at a parts store and some hose clamps to fit, and put it on...

 

The Black box is your EVAP Canister.

 

Can this hurt my gas mileage like this?

 

EVAP canister. All the EVAP system does is catch fuel vapor from where your fuel evaporates inside the tank and then burns it in the engine. As for the mileage, think about it. If the fuel evaporates and there's nothing to "catch" it, then its wasted. So if you have something to "catch" it, then that's fuel that's not wasted.

 

what year is your rig? something like that should cause a large evap leak code at least if its OBDII. just get some generic hose and cut it to fit.

 

It's a 99

 

Got it fixed... It was easy