hey guys,
info, 1997 jimmy 4.3 auto 4x4

name this vacuum line and win a prize.



it runs under the engine to an unknown location.
truck runs fine except for bad gas mileage and a p0440 code.
theres a black plug in it.. not sure if it came like that or if previous owner did something...
please let me know what you think it is

 

Looks like the vent line for the front diff.

 

so do i jest leave it?
is it a special plug in it?

 

Just leave it, that is a breather in the end and you want it up high so it does not suck water in.

 

That's exactly what that is.
Just leave it. If it isn't attached to something to keep it up as high as possible, you might want to find a way to attach it (zip tie, etc).