Topic: Jeep just shuts off. Need some help YJ

[chardrc]

the 2 hard plastic vacuum lines coming from the transmission area come from the trasfer-case and are used to engage and disengage the central Axle disconnect on the front axle. those lines are long gone on my jeep (previous owner went with a cable actuator) I found a diagram of the system (see below) it should be the same for all yj's so if those liens come from the transfer-case and that diagram doesn't help someone else can chim in that is more familiar with the CAD vacuum system (from the diagram i can't tell where it gets the vacuum unless the t-case creates vacuum somehow)



as for what connects into that purple hard line, its either the red #1 line going the the vacuum solenoid, or the blue line that T's into the evap canister (im leaning towards the blue line). i don't remember which but as long as the tube size matches it shouldn't matter (as long as what needs vacuum gets it).. are there 2 or 3 hard lines that go behind the motor (im having a hard time remembering)

edit for your new post: test your tps and iac as you mentioned... when you turn the jeep off the iac motor should fully extend so that the jeep has extra air to start. (have you tired to start it while holding the throttle partially open to give it some air to test your lake of air due to no vacuum leak theory)


also make sure you plugged in the egr vacuum solenoid (it wasn't in your pic, it would make it idle like crap since i think if its not pluged in it lets vacuum go through which engages the egr but shouldn't stop it form starting would just make it run rough)

[chardrc]

(from the diagram i can't tell where it gets the vacuum unless the t-case creates vacuum somehow)

looking at it again i would guess that it probably gets vacuum form the line that ends with a check valve, which i have no idea where it goes to.

[Backroads]

The evap purge line is there with the second fittig Td into it as well. That goes to a thicker hardline and into the TB. Thats all right and like the diagram shows.

As for the Xfer case and 4wd, I plan to do away with that anyways so I will just leave those go for now, unless I should cap them or something else?

There is a check valve in the engine bay, under the battery area that doesnt have anything plugged into it. I didnt know if that purple circled line should go to that? Theres really nothing else over there I'm seeing that it should go to. Its a pretty large line so it looks like it should go to something that needs a descent amount of vacuum.

[chardrc]

As for the Xfer case and 4wd, I plan to do away with that anyways so I will just leave those go for now, unless I should cap them or something else?

mine where just cut off after that multiple hardline connector near the evap can. would probably be a good idea to cap them off but i haven't

There is a check valve in the engine bay, under the battery area that doesnt have anything plugged into it. I didnt know if that purple circled line should go to that? Theres really nothing else over there I'm seeing that it should go to. Its a pretty large line so it looks like it should go to something that needs a descent amount of vacuum.

only check valve on the passenger side i remember is the one circled in my pic with the "4?" which i think should be connected to the 4? from your vacuum solenoid. but the other end could go to that hard-line (which makes sense... im kind of at the point where i don't remember any more details (and studying for 2 midterms this weekend has my brain working overtime)

[Backroads]

Everything aside from a crappy exhaust is finally kosher.

Thanks chadrc for all the help, I really had everything screwed up!

[chardrc]

no problem.. gotta keep the tbi's running we are vastly outnumbered  . lol.. just curious, what ended up being the more recent problem with not starting, was it a sensor or more vacuum lines..   

[Backroads]

as ashamed to admit it...I now know all about the YJ gas tank recall 

My guage was reading over 1/4 tank of gas, so I assumed it had gas!! Well it wasnt running, and randomly shutting off because.....I HAD NO GAS!

It all makes perfect sense now, so my next object issue is to drop the tank and replace the gasket and whatever else is leaking under there as well as the sending float.


Only issue I'm having now as far as vacuum is that I only have heat on defrost, no matter what position the operating lever is in...I gotta recheck all that and see whats going on there..

[Jeffy]

Strange since the vacuum control should be independent to the Defrost/Heat/Vent control.  You should be able to manually set the heat by switching the vacuum lines.  The manifold is right above the ashtray behind the dash.

[chardrc]

someone had found that there is a difference between the yj and xj vacuum systems and i figured id put the answer here to keep the tbi vacuum stuff in 1 area.. thanks to my recent find of a 1990fsm i found a diagram for the xj system. basically the xj uses ccv system where yj uses pcv. and some things plug into the manifold rather than the tb. i didn't take the time to color code it but its basically the same as the ones on the last page.

[ropeman]

This thread is what helped me find this board.  I need some additional info to get everything just right on my 1989 YJ 2.5L

In this picture where does the hardline connect? 

http://img829.imageshack.us/i/vacuumlines1.png/

On my 4 banger the line is part of the group that goes behind the head to a block of lines one the passenger side.  I guess the port on the intake and vacuum line isn't shown in the emissions diagram because the small port goes inside to the dash and the bigger line goes to the axle disconnect?  That is the only place I can figure it would go because my Jeep doesn't have the vacuum disconnect and this line is plugged.


Next, is the blue thing circled in this pic the 4wd indicator light?

http://img576.imageshack.us/i/vacuumlines2.png/

[chardrc]

the blue thing is the 4wd light sensor (part of the vacuum axle disconnect stuff)... found another vacuum diagram in the parts catalog that actual shows the true routing of the hard lines. i color coded it to match my previous images (with a few differences for clarity) hope it helps. the hard line circled in purple in the photo you quoted needs to have a 90 degree elbow connecting it to that orifice in the manifold. the other end goes around the back of the motor and then goes to the front axle vacuum disconnect stuff or it goes into a small plastic line with a check valve that goes through the fire wall. i forget which...

edit: image was re sized in this post, if you double click and view image form photobucket you can enlarge to 100% to see it better

[sharpxmen]

split it in two for better viewing:

[ropeman]

That is a great picture of the vacuum hoses!  It's so hard to look at the regular diagram and follow how the lines are supposed to run.

Now the other question I had was about the vacuum switch, part 19 on that diagram.  Mine has 1 port on top and two ports on the bottom.  I haven't found anything that shows where the 3rd port connects to.  

Thanks for the help!

[chardrc]

only one of the bottom 2 ports is used. the other is one has a cap over it.

[Backroads]

Awesome diagram, that actually looks like what you see under the hood instead of those haynes manual diagrams!