Broken line coming from firewall

DTYJ94

New Member
Joined
Dec 3, 2022
Messages
3
Location
Birmingham, AL
Got a 94’ YJ 2,5 L that I’ve been working on for a few weeks. It’s been sitting in the woods for close to 10 years. I’ve got it running again, but have a ton of work to do. The thermostat gauge wasn’t working, so I was installing a new temp gauge sensor. While pulling the “wires” away so you could get a socket to unscrew the new sensor. In the process I broke 2 lines. They are obviously brittle. One of the lines I broke appears to be a small vacuum like to the MAP sensor. Im going to try to connect the old lines together with some small tubing but have and shrink wrap for now. But, one of the other lines broke that is to the right of the firewall closer to the drivers side. I haven’t cut into it to see if it’s wiring or another vacuum line. Could someone tell me what this line is and what it goes to. Im trying to trace to its source, but not sure where it connects. Is it a vacumn line or is it an electrical line that goes to the manifold or something like that? Thanks have this a Chilton manual, but I haven’t found it so far. Any feedback would be greatly appreciated. See photo for the line I am referring to please. Thanks for the help!

43F4F492-FFE8-4853-B352-DA2CF3AECC7D.jpeg
 

Flyer58

YJ Enthusiast
Joined
Apr 12, 2020
Messages
723
Location
Magnolia, Texas
Without going out to look I believe that line goes inside for an up-shift arrow light in the warning cluster and maybe a vent control.

It should connect to a T-fitting coming off the rear intake manifold port. The other line goes to the vacuum control switch on the transfer case for the 4WD activation.

I'll check my 92 later.
 

Flyer58

YJ Enthusiast
Joined
Apr 12, 2020
Messages
723
Location
Magnolia, Texas
As I mentioned for my '92, that vacuum line goes to a T-fitting on the rear of the intake manifold and the other line goes to the transfer case switch

1672178699422.png
 
  • Like
Reactions: DTYJ94
OP
DTYJ94

DTYJ94

New Member
Joined
Dec 3, 2022
Messages
3
Location
Birmingham, AL
Thanks for your reply. I ended getting some fuel and air lines from my chainsaw carb rebuild kit and slipping it over broken vacuum line. I slipped some heat shrink over the line and just heated so slightly so that the line remained open. I broke the line to the map sensor and fixed it the same way. It fired right up and has ran well for days now. I appreciate you sending the photo and taking the time.
 

machoheadgames

Certified YJ Researcher
Supporting Member
Joined
May 19, 2020
Messages
1,512
Location
Dallas, TX
The part you broke goes to the heater control panel. When the heater control panel is put in any mode besides “OFF”, a vacuum motor up behind the glove box lets fresh air into the heater system. That is the only portion of the heater that is vacuum controlled, the rest is all cable operated.

The other vacuum line attached to the tee near where that line broke is for actuating the front axle disconnect in 4wd.
 
  • Like
Reactions: DTYJ94
OP
DTYJ94

DTYJ94

New Member
Joined
Dec 3, 2022
Messages
3
Location
Birmingham, AL
Thanks for y’all’s help. I’ve been searching manuals and the forum for what I think is another broken vacuum line. I noticed that this line has been broken/disconnected since I acquired this 2.5 YJ. This line is on the passenger side, near the battery. The line next to it goes to the 4wd vacuum located on the manifold. Can someone tell me what this line does and possibly the proper name for it so I can get it fixed and reconnected to wherever it goes. I can find it in my manual and I’ve been searching the service manual I downloaded from here. If anyone can tell me what this is and where it goes. I suspect it’s possibly part of the 4wd drive, but I don’t know. I hate to ask, figured I would try here to see if anyone knew. Some photos of other Jeeps show this vacuum line going downward, but haven’t been able to trace it.

F6AF1311-8906-4002-B13F-B73A51A84787.jpeg
 

Flyer58

YJ Enthusiast
Joined
Apr 12, 2020
Messages
723
Location
Magnolia, Texas
It's all part of the 4WD system. You may see some color bands to help identify the vacuum lines which lead to the switch transfer case and back up to the front axle. M vacuum lines were in different length segments and connected with short rubber tubes. That might have been a repair.

Here's a basic schematic for the lines that's pretty easy to follow.

18.jpg
 

machoheadgames

Certified YJ Researcher
Supporting Member
Joined
May 19, 2020
Messages
1,512
Location
Dallas, TX
Thanks for y’all’s help. I’ve been searching manuals and the forum for what I think is another broken vacuum line. I noticed that this line has been broken/disconnected since I acquired this 2.5 YJ. This line is on the passenger side, near the battery. The line next to it goes to the 4wd vacuum located on the manifold. Can someone tell me what this line does and possibly the proper name for it so I can get it fixed and reconnected to wherever it goes. I can find it in my manual and I’ve been searching the service manual I downloaded from here. If anyone can tell me what this is and where it goes. I suspect it’s possibly part of the 4wd drive, but I don’t know. I hate to ask, figured I would try here to see if anyone knew. Some photos of other Jeeps show this vacuum line going downward, but haven’t been able to trace it.

View attachment 120897
It's part of the 4wd, and it isn't broken.
 
  • Like
Reactions: DTYJ94