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Unread 09-01-2014, 07:04 AM   #1
emersonsc
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1990 YJ Wrangler 
 
Join Date: Dec 2010
Location: Allen Park, MI
Posts: 37
Missing vacuum lines, running rich, nutter bypass

Since I got my jeep it's been hard to start, tends to run likes it's flooded until it's warm, and runs rich. Now I know I need to replace the stock carb (a weber 38 will be ordered as soon as funds are available) but until then I gotta make the stock work.

I've noticed after tons of reading and looking at diagrams and simply by looking under the hood I have several vacuum lines missing. Ones I can recal off the top of my head include one on the carb (hooked to a valve that has a plunger that pushes out towards the throttle linkage from the front), two missing from the yellowish and green valves on the fire wall, and at least 3 of the 5 from the part coming off the manifold that has 5 nipples.

My first question is, am I right for assuming it's running rich because of all the missing vacuum lines?

2nd, the nutter bypass includes bypassing the computer, but do all of the vacuum still need to be present and connected properly to work?

Thanks again for all the help you may be able to offer

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Unread 09-01-2014, 07:13 AM   #2
Old4X
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Nothing wrong with the OEM carb, except it is 25 years old. Have it rebuilt and new throttle shaft bushings fitted and it will be fine.

There are 12 to 20 adjustments on a carb this size that must be correct for it to work correctly, and this includes the motorcraft and weber units as well as the OEM.

If you are running rich, the carb needs overhauled and set up correctly.

Your vacuum system needs to be hooked up properly as well.

Info here:

http://home.sprynet.com/~dale02/list.htm
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Unread 09-01-2014, 08:20 AM   #3
Mike Romain
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If you read the how to nutter bypass thread it will give you the vacuum lines you need. Lots like the ones you mentioned aren't needed. It also goes over the carb tuning.

Your carb likely just needs a kit. A tune at least. Normally they run too lean at start which causes a miss which blows raw gas through smelling just like it is running rich.

Basics, make sure the gas filter sits level with the return line up top and the carb line in the center. You then need to pump the gas at least once to the floor to prime it and to set the choke. Then with foot off the gas start it. It should go to high idle and start climbing. (When setting high idle on a warm engine it should be 1750 rpm or so) After a bit, you tap the gas and the idle will drop half way, then when it warms, another tap gets to idle.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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Unread 09-01-2014, 08:24 AM   #4
chris142
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make sure to really clean out those 2 emulsion tubes.those plug up and it wont idle well if at all
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Unread 09-01-2014, 09:46 AM   #5
emersonsc
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Location: Allen Park, MI
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I swear I had read in another thread that the carb inlet had to be up top and the return below. I'll have to spin it around and try that out.

The carb was rebuilt prior to me picking it up, but I'm not sure if it was just taken apart and cleaned or if a rebuild kit was used.

The nutter bypass only mentions bypassing the distributor to advance timing but it does bypass the computer which I would assume is the only part of that whole system that needs it?

Would doing the nutter help my issues on top of rebuilding the carb?
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Unread 09-01-2014, 12:40 PM   #6
dancytron
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Yes, the nutter could help. With the computer (pre-nutter), you need to have all the sensors working for it to run right. The nutter takes the sensors out of the equation and lets you tune it like a 1979 CJ-7.

Try the Nutter first, since it is easy and free. Make sure you don't have any vacuum leaks. If you haven't done it yet, do a regular plugs, wires, distributor cap and rotor tuneup. You can use better Ford parts for the tuneup. http://www.jeepforum.com/forum/f8/i-...nitive-669495/ See how it runs.

Then decide if you want to rebuild the carb or get a different one.

Good nutter bypass link. http://www.jeepforum.com/forum/f8/ho...bypass-522262/
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Unread 09-01-2014, 02:11 PM   #7
Mike Romain
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Quote:
Originally Posted by emersonsc View Post
I swear I had read in another thread that the carb inlet had to be up top and the return below. I'll have to spin it around and try that out.
It is to prevent vapour lock on a hot shutdown. Any vapours produced get blown off the top of the filter back to the tank. If it is at the bottom, then gas will drain out of the lines and stock carb's float bowl back to the tank making it a bugger to start up.

Quote:
The nutter bypass only mentions bypassing the distributor to advance timing but it does bypass the computer which I would assume is the only part of that whole system that needs it?

Would doing the nutter help my issues on top of rebuilding the carb?
Yes it bypasses the computer, but it won't magically fix a sputtering cold carb. I always recommend folks make them run well as they can first before doing it. It won't make anything worse, but if it has complications and it wasn't running to start, well... Yours runs at least.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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Unread 09-02-2014, 02:14 PM   #8
emersonsc
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Location: Allen Park, MI
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After doing some reading from the links you guys shared I decided to crawl under the hood and check out the condition of my vacuum & emissions. I also made a call and confirmed the carb WAS rebuilt WITH a rebuilt kit the day before i picked it up (i got it from family so i have no reason to not believe this statement). It seems as though a good portion of the vacuum system was removed. Im missing both pulse air valves, the vacuum solenoids that mount on top of the valve cover, multiple lines are disconnected from the CTO, the decel valve is gone, the PCV valves arent connected properly due to the decel and pulse air valves missing, the 4" and 10" vacuum switches are disconnected, the EGR is present but the vacuum line is disconnected, and the delay and vacuum reservoir that the 10" switch connects to are also missing.

according to the Sprynet page, my Jeep is running exactly as described when the vacuum/emissions/ECM goes bad (rough start, "rich" running conditions due to the stepper motor forcing to go fully forward, large puffs of smoke when it starts, and bogging/misfire during "warm up").

My question is, since it runs now with out all the vacuum lines and emissions working right or at all, would the nutter bypass correct my issues or would i still need to find the missing parts and lines? I would say a good 80% of the vacuum parts are gone. Ive also included some pictures to show whats missing...


The 4" & 10" switches that are disconnected:


The spot where the vacuum solenoids should be mounted:


Where the line that controls the EGR and one the goes to the CTO should be connected:


Only one of these lines belong connected to the CTO:
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Unread 09-02-2014, 02:32 PM   #9
dancytron
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It will run without most of that stuff if you do the Nutter bypass. You'll need to get the PCV fixed up. The EGR and Vapor Canister would be nice but can wait until you get it running right.

This link from the spynet page shows what runs into and out of the computer (useless after Nutter) and what runs without the computer.

http://home.sprynet.com/~dale02/control.htm

Your only choices are do the Nutter or get all of that stuff hooked back up and working properly.
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Unread 09-02-2014, 02:38 PM   #10
emersonsc
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Quote:
Originally Posted by dancytron View Post
It will run without most of that stuff if you do the Nutter bypass. You'll need to get the PCV fixed up. The EGR and Vapor Canister would be nice but can wait until you get it running right.

This link from the spynet page shows what runs into and out of the computer (useless after Nutter) and what runs without the computer.

http://home.sprynet.com/~dale02/control.htm

Your only choices are do the Nutter or get all of that stuff hooked back up and working properly.
I traced the PCV again and it IS connected properly. I overlooked a line. The vapor canister is connected as far as I can see. The EGR seems to me strictly for emissions, and since I live in michigan where we have zero emissions testing I'm not worried (unless it helps with performance, but if the gasoline EGR is anything like a diesel, I know it isn't a performance gainer)

Looks like I'll be finding a timing light and getting the nutter done ASAP. Fuel mileage is killing me right now and the neighbors aren enjoying listeni to this beast try to start at 2am on my way to work
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Unread 09-03-2014, 08:43 AM   #11
Mike Romain
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When the stepper pins are full forward, that is the ECU trying to make it run richer because the O2 says its lean. Usually implies a vacuum leak or a lean condition the ECU is trying to make up for.

Pins full in, carb is forcing rich, pins all the way out, carb is forcing lean. They are air bypass pins.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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Unread 09-04-2014, 07:05 AM   #12
emersonsc
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Join Date: Dec 2010
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Quote:
Originally Posted by Mike Romain View Post
When the stepper pins are full forward, that is the ECU trying to make it run richer because the O2 says its lean. Usually implies a vacuum leak or a lean condition the ECU is trying to make up for.

Pins full in, carb is forcing rich, pins all the way out, carb is forcing lean. They are air bypass pins.
I've read a couple nutter bypass write ups and some say adjust pins half way some say full in. Wouldn't I rather have mid way to avoid the already rich condition that's causing my issues?
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Unread 09-04-2014, 01:03 PM   #13
wrjr4
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Do the nutter it will save you a lot of headaches later. you will still need the line to the dist and vucuum to the brake booster from the carb. Be sure to cap off any ports that are not being used. As for the carb not a big fan of the carter bbd if you can get it adjusted and working you can buy some time. When i did the nutter i also went with the motorcraft 2100 rebuilt it with a #50 jet i believe and it ran much better. They are easy to come by at any JY from a ford.
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Unread 09-04-2014, 01:28 PM   #14
dancytron
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Location: st. louis
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Quote:
Originally Posted by emersonsc View Post
I've read a couple nutter bypass write ups and some say adjust pins half way some say full in. Wouldn't I rather have mid way to avoid the already rich condition that's causing my issues?
I did halfway. Most recent posts say halfway.
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Unread 09-04-2014, 07:57 PM   #15
Mike Romain
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Quote:
Originally Posted by emersonsc View Post

I've read a couple nutter bypass write ups and some say adjust pins half way some say full in. Wouldn't I rather have mid way to avoid the already rich condition that's causing my issues?
Half way for sure. That means the pin shaft should be showing 1/8" before the taper from the back wall. I even had email correspondence with John nutter about that way back when. He only used it off road and didn't care about mileage or emissions. They run best centered like the computer had them when all is right.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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