What's this hose do?

So when I popped my hood to start replacing my fuel filter yesterday, I noticed this hose had disconnected (see photos, I had reconnected it in the first photo). Looks like the pipe comes from the air filter box and the other end goes to an unknown (to me) box. I had to run to store to grab some flanged m8 x 1.25 bolts and grabbed a replacement hose as both ends had split and the one had come loose.

In related news, once I've replaced the fuel filter, is there anything I need to do before starting her up again?

 

Looks like part of the evaporative emissions system.

 

Um... yeah. I believe that's part of the EVAP system. Which will throw codes and a check engine light. Someone correct me if I'm wrong.

Don't take my word for it

 

I have now googled what an EVAP system is... makes sense. It hadn't thrown any codes (although the airbag light has blinked slowly since I bought the truck) but It should be right as rain now. Anyone know anything about the fuel filter question?

 

I don't think you need to do anything special once it it installed. Just start it up. It will probably crank for several seconds as the fuel system pressurizes and fuel makes its way to the motor.

 

The fact the Light did not light right away is not a Good Sign

The bulb does light when you turn the ignition on?

 

That line is part of the EVAP system, but it’s not as important as you think. It is a filtered air inlet into the charcoal canister, which is why the other end of that line attaches to the filter box. It will not cause a check engine light by having that line removed.

 

There may be a hose diagram under the hood. As you can see, one end terminates at the evap box, the other end might be at the air filter box.

 

Evap line, just buy a replacement from a hardware store.

No special procedures after a fuel filter. Some people cycle the key a few times, but it will start just fine.

It's the "from air cleaner" line. This sticker might be on your hood.

 

Now my 3.4 does not have that hose going to the air filter box is this only a 4 cylinder thing?

Then it might have been removed

 

1995 3.4 has it running along the cowl.

 

Thank you! I noticed mine was split on one end and in need of being replaced, but didn't know what hose it was. This was helpful.