91-95 4.0 YJ Guys, where is the vacuum source for your 4WD?

[Ted_Grevers]

On the 87-90, it connected via a set of solenoids on the top rear of the valve cover, then down to the switch on the transfer case. Since I've change to the Mopar MPI, I got to thinking, where would someone connect their 4WD vacuum source? Is there a valve on the intake manifold, or does it connect somewhere else? I don't use any of the vacuum disconnect on my YJ at all, but am curious where it ties in on the newer YJs. I'm doing a little research. :)

-Ted

[Ted_Grevers]

No one owns a 91-95 4.0 YJ?

This isn't even a tech question..... :confused:

[jjunior887]

when I did my 4.0 swap, I used one of the vacuum fittings on the intake manifold(on the side next to the throttle body) and ran a line down to the 4WD harness. -James

[Ted_Grevers]

Thanks for the info, just to confirm, it was one of the ports that faced upright on the top, rear of the intake. Before you did the swap, was the XJ port blocked with a cap?

-Ted

[jjunior887]

The one I used was blocked off with a cap but it was on the side of the manifold, i think there are 3 of them but the other two were used for other stuff. It really doesn't matter where you hook it to as long as it has vacuum.

[Ted_Grevers]

Thanks again for the info. I am thinking that I will try and run it direct. Do you recall if you used any kind of in-line filters between the engine and transfer case switch? I am thinking they would have one, but not sure if they did. Ultimately, I'll use this for a vacuum gauge and some other things as well.

Thanks again,

-Ted

[jjunior887]

I'm pretty sure the 4WD vacuum harness has a check valve on the end of it if I remember correctly, I'm sick and it's too cold for me to go out and check. -James

[HEEPJEEP]

Oh, forgot to tell you. Those vacuum lines are on their way to you.

-Dave

[Ted_Grevers]

-=- originally posted by HEEPJEEP -=-
Oh, forgot to tell you. Those vacuum lines are on their way to you.

-Dave

Excellent, and thanks!

-Ted

[hadfiiw]

Hi Ted,

So it looks like there are two extra VAC fittings on my Intake (using the MOPAR MPI to upgrade my 87 YJ). If one is for the 4WD, did you use the other for anything or just cap it off? (looks like the other two are for the regulator and the MAP sensor but I still have an extra port) :puzzled:

Thanks

[Ted_Grevers]

-=- originally posted by hadfiiw -=-
Hi Ted,

So it looks like there are two extra VAC fittings on my Intake (using the MOPAR MPI to upgrade my 87 YJ). If one is for the 4WD, did you use the other for anything or just cap it off? (looks like the other two are for the regulator and the MAP sensor but I still have an extra port) :puzzled:

Thanks

I capped them both.

When I installed my MPI setup, I had a posi-lock, so, I didn't need to set up the vacuum. Now, I don't have my posi-lock any more, I have a solid front Dana 44, with no disconnect at all. So, you can just cap them off, and not worry about them.

-Ted

[hadfiiw]

Thanks Ted! :beerchug:

[jjunior887]

One of them is most likely for the evap cannister(at least it is on the newer ones), another use could be the vacuum for the heater. Just throwing that out there in case you are wondering.

[hadfiiw]

Well, after more digging I found out I was missing a page in my MPI instructions. Whops! That would do it.

The missing pic is saying that the "T" fitting goes to the Fuel Pressure Regulator and the Evap Canister. The next one goes to the air tube on the back of the valve cover. Then the MAP sensor vac fitting, the MAT sensor plug (not a vacumn fitting) and then a spare for things like 4x4, climate control, or cruise. :spinhead:

Thanks everybody :beerchug: