Carburetor Woes

[88YJ6]

Ok so I just rebuilt my POS Carter 2 bbl and went to hook up vaccuum again and have a port on the back of my carb right below the stepper motor that is open and I cant figure out what goes there?

Now I also cant get the thing to idle right. Ive read a bunch of stuff online and have figured a couple things out for myself. Number one my needles coming off the stepper are all the way out and not really jumping around which I believe they should be based upon my research.
Number two, I tried unplugging my O2 sensor to see if it was doing anything, with the engine warm. Didnt make any difference, so I am assuming my O2 sensor is shot.
And to wrap it all up, I found out I have an exhaust leak, because working on those manifolds is a bundle of joy!

 

[TerryMason]

Did you manage to get this figured out? I found this when looking for your problem

Rough, unsteady idle problems are all too common with the Carter BBD on the 258 CID engine. This can be caused by several different things, but the most common is a too-rich or too-lean fuel mixture. You can get a clue to which it might be by removing the lid of the air cleaner and looking down at the metering pins. If they are all the way forward, the mixture is too lean. If they are all the way back, it's too rich. This assumes of course that all the other systems are working. If it's too lean, check for air leaks around the carburetor base and the intake manifold gasket. Check all vacuum hoses for cracks, breaks, and leaks. A bunch of little leaks add up to one big one. If the hoses appear cracked and aged on an older engine, it would be worth your while to go to the auto parts store and buy new hose and just replace them all. It's inexpensive and not hard to do. Check the Evaporation Canister for correct operation. It should not be purging at idle.

 

[88YJ6]

Yeah I read that, and spending some more time doing diagnostics im fairly sure i not only have a bad egr vacuum diaphragm but also a burned valve. I can suck air through the vacuum line running to the egr at idle which i think is contributing to the fast idle even though my mixture is good based upon looking at the metering pins on the stepper, while the curb idle screw is all the way out.
Then I think the egr valve is bad because my idle is full of hickups, etc

However I still cant figure out where that port on the back of the carb right below the stepper motor is supposed to go to...anyone?
Thanks for the input

 

[ursman]

As the diagram above shows (which is mind numbing to look at), You should have one port going to the PCV tee'd off to the decel valve and upstream AIR tube. The other one should go under the air cleaner to the TAC sender and vac chamber.

Here are some good links for info on the Carter and emissions system.

A Primer on the Jeep 258 with Carter BBD & Pulse Air Emission System - - Jeep at Off-Road.com
Easy Fix for Jeep 258 Carter BBD Idle Problem
The "Nutter" Bypass

This should give you enough info to troubleshoot:shades:

 

[88YJ6]

Ok I am thankfull for everyones input but as I stated I have three manifold ports not just two.

 

[ursman]

I still have my old carter w/ most of the lines still attached. I will take a look at it tonight and see if I can figure it out. BTW, make sure that your EGR, CTO and PCV are on "ported" vacuum and NOT manifold. This will cause the engine to run terrible (speaking from experience).

 

[cerial]

Ok try this remove all the lines going to the carb and loop the emission system(temporary) Manifold-manifold/ported-ported.
Then block off all the carb and except the vac advance(run a additional peice of hose to the distributor). With the engine cold disconnect the stepper motor.
Have the idle set high and run the engine(around 1800) and check for leaks around the manifold.
Run the engine rich(3 turns)(dark smoke out pipe) then move it back while adjusting the idle.
To try to get a idle around 1200 and put it in drive(don't hit the gas yet)in drive you are going for 800
Hook up the emissions and test park/drive idle rpm's then in drive bump gas(if it stalls leave the back port open(under the stepper if not plug the port)

runs good but you cant get the rpm down
check for leaks out of the side where the linkage is.
try squeezing off a fuel hose(with vice grips- this way you can see if you need a reg) and play with the mixtures.
also try disconnecting the choke and setting plate by handaand see what resukts you get
Test the egr

 

[JJs 88 Wrangler]

Cerial,


When you say "Run the engine rich(3 turns)(dark smoke out pipe) then move it back while adjusting the idle" do you mean 3 turns out from bottom, and also are you adjusting both screws evenly? I just had my block and head rebuilt over the past winter and dropped it in during the spring. I also bought a rebuilt carb, but cannot get it adjusted properly. Thank You for any info..

JJ