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Unread 03-18-2010, 07:45 AM   #1
PINKANDBLACK
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1990 YJ Wrangler 
 
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Nutter Bypass Left Me Disabled

I have the stock carb on a 1990 I6 yj. I skipped the first part of the bypass where you mess with the carb cause I was unsure what to do and my mechanic said it was probably set somewhere around what I need. I cut the right wires at the firewall and also the purple and orange wires underneath the windshield washer box, connected orange to orange and purple to purple, and it wont start up. Under the windshield washer box I connected the wires from the firewall to the wires going into that stone looking box under the coolant reservoir. Whats in there?

Some of the instructions (I printed off multiple write-ups on the nutter bypass) said to reconnect some of the vacuum hoses on the carb to different spots, and other instructions said nothing about vacuum hoses.

Can anyone help me get started?

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Unread 03-18-2010, 07:49 AM   #2
spawnofsatan
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your suppose to connect the wires coming from the Dist. to the Ignition Module under the coolant box. your by passing the comp. under the dash.
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Unread 03-18-2010, 07:59 AM   #3
PINKANDBLACK
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So I connected the wires from the distributor to the wrong side of the cut wires under the windshield washer box? I looked like the other wires were headed toward the computer so I figured I would go the other way. Ill try rewiring.
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Unread 03-18-2010, 08:05 AM   #4
spawnofsatan
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Bofore and after pick












[IMG]file:///C:/DOCUME%7E1/RLebuna/LOCALS%7E1/Temp/moz-screenshot.png[/IMG]Here is the pic.
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Unread 03-18-2010, 08:05 AM   #5
Elsahara
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Quote:
Originally Posted by PINKANDBLACK View Post
I have the stock carb on a 1990 I6 yj. I skipped the first part of the bypass where you mess with the carb cause I was unsure what to do and my mechanic said it was probably set somewhere around what I need. I cut the right wires at the firewall and also the purple and orange wires underneath the windshield washer box, connected orange to orange and purple to purple, and it wont start up. Under the windshield washer box I connected the wires from the firewall to the wires going into that stone looking box under the coolant reservoir. Whats in there?

Some of the instructions (I printed off multiple write-ups on the nutter bypass) said to reconnect some of the vacuum hoses on the carb to different spots, and other instructions said nothing about vacuum hoses.

Can anyone help me get started?

Check your connections YouTube - How to Do It: Basic Soldering
Solder your connections for a consistent and long lasting connection.
Also make sure its the right wires, if you didnt pull them out of a wire loom then ive heard issues where the wires actually change color, rare but possible.

A bad connection is def can be source of a "no start" issue. Also isnt there a step to change timing? 8* advanced? DO NOT QUOTE ME but I could have sworn that you need to advance your timing. Read some of the stuff you wrote up. Dont recall any vacuum lines being removed but just because i dont recall it doesnt mean it isnt a step.

Good Luck
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Unread 03-18-2010, 09:26 AM   #6
PINKANDBLACK
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Yea I pulled the loom apart and traced them to the firewall. I read that the timing can be 8* (+/-2). I set it at 10 first cause thats where it was idling best. Even if thats the problem it seems as though the jeep should start up, even if it runs rough.

I cut both wires right at the ignition module. In the diagram below it says that both orange wires can be cut from under the dash. Does this matter?

So the ignition module is that block that is bolted to the fender well under the coolant fluid reservoir? This is where I should run the distributor wires to right? Im running out of wire down there! Im working with the crappiest butt connectors.

Could the problem be that I did'nt adjust the stepper motor needles in the carb to the right position ( I guess this tricks the ECM?)

Ill screw around with it some more and check back in.

Thanks guys
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Unread 03-18-2010, 09:41 AM   #7
Fernando
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How did you set your timing if the engine does not start?

If you set your timing at idle before nuttering it to 8*, then it does not start now because you do not have any ignition advance.

Did you set the timing before the Nutter according to the manual?
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Unread 03-18-2010, 09:54 AM   #8
Elsahara
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Quote:
Originally Posted by PINKANDBLACK View Post
Yea I pulled the loom apart and traced them to the firewall. I read that the timing can be 8* (+/-2). I set it at 10 first cause thats where it was idling best. Even if thats the problem it seems as though the jeep should start up, even if it runs rough.

I cut both wires right at the ignition module. In the diagram below it says that both orange wires can be cut from under the dash. Does this matter?

So the ignition module is that block that is bolted to the fender well under the coolant fluid reservoir? This is where I should run the distributor wires to right? Im running out of wire down there! Im working with the crappiest butt connectors.

Could the problem be that I did'nt adjust the stepper motor needles in the carb to the right position ( I guess this tricks the ECM?)

Ill screw around with it some more and check back in.

Thanks guys

First, if your timing is screwed up, it will most def not allow the engine to start. I would adjust the stepper needles, but i dont think it would affect the start up. Those connectors arent that bad but i would double and triple check all the connections(take your time, with pics in hand and retrace everything!). Seems like you have the correct wiring but cant be 100% sure. Pics would help.



Quote:
Originally Posted by Fernando View Post
How did you set your timing if the engine does not start?

If you set your timing at idle before nuttering it to 8*, then it does not start now because you do not have any ignition advance.

Did you set the timing before the Nutter according to the manual?
He must have set the timing to 10* before he started the bypass. What I would do IMO is have a friend help, one guy in the engine bay and one in the cab (once you have checked all wire connections) and see if our getting spark(pull a plug and see if it has spark), adjust the timing (only small changes please) get it to sputter and at least barely run. Then throw a timing light on and adjust to where you need it (read paperwork for exact spec).

Also when you started this, most right ups explain you only need so many vacuum lines to actually make your engine run. So if you took any out, make sure it didnt effect the Vacuum Advance for the distributor. To my knowledge there is no ts or anything else on that line but....?

Last edited by Elsahara; 03-18-2010 at 09:57 AM.. Reason: cause it needed fixin'
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Unread 03-18-2010, 10:38 AM   #9
Elsahara
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This guy has mentioned something I hadnt considered. Not entirely important to not starting but about the vacuum lines for the Vacuum advance. Also where you timing should be and how to use a vacuum gauge to set timing.


Quote:
Unfocused] The vacuum advance on the distributor on the stock engine is connected to manifold vacuum. When nuttered, it should be connected to ported vacuum. I assume you did this, but if not here's a link with lots of info for your engine including vac diagrams which will help you locate ported vac:

Table of Contents

Regarding man vac vs ported vac, they act opposite one another. At low rpms man vac is high and ported vac is low; at high rpms ported is high and man is low. So if you didn't swap the vac connected to the dist advance you're not getting proper high rpm advance which could cause your problems.

As to timing, select the Ignition Tweaking topic in the middle column of the above link and then click the right diagram when the page comes up. You'll find a description about setting the timing using a vac gauge. That's the way I do it and I think it's better than using a timing light on older engines. I'm at 8800 feet elevation and specs say to set timing at 16*. I used the vac gauge method and checked it with the timing light at it was at 19* with plenty of power and about 21.5 mpg on the freeways at 70 mph. I haven't used a light to set timing in years, I only use one to check where it's at after setting with a gauge.

In that you're going to have the man vac line from the distributor advance disconnected anyway, simply leave it connected to it's source near the carb and plug it; then you'll always have a ready source of man vac for your gauge or whatever.

Hope this helps.

Last edited by Elsahara; 03-18-2010 at 11:31 AM..
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Unread 03-18-2010, 11:04 AM   #10
PINKANDBLACK
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^^I think he is talking about the same vacuum hose changes that i have written down some where...the distributor hose gets disconnected from the carb at the T, plug that side of the T, and then you connect the distributor line to the ported vacuum line using a T.

I just rewired it back to normal (at this poing Im just twisting wires together), started it up and got it idling ok, then I screwed in the idle jets. I didnt get to far untill it stalled out, so I kept screwing them in a little and then cranking it over and repeated this process untill I thought they were in pretty far. It said something about being able to see the stepper motor needles in the carb when you do this but I dont know what the heck a stepper motor needle is so I couldnt identify them. Then I rewired the orange and purple again and it still wont start. it cranks over but thats it.

As for the timing, I set it at 10 before I started this whole thing and it was running great. Should I reset it to 8? The instructions say set it to 8 plus or minus 2*.

I havent done anything with the vacuum lines yet, should I give that a try? I can always reverse anything I do so Im not worried about that. Plus unless this carb runs way better after the bypass then Im switching to a motorcraft. My carb runs like dirt now.

I think I may be screwing up the idle jet part which tricks the ECM.
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Unread 03-18-2010, 11:06 AM   #11
Fernando
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I guess there is a lot to be discussed about manifold vs ported vacuum. I work with manifold vacuum, following the advice of JeepHammer, and I have absolutely no issues. I can not explain to you why manifold vacuum is better because I do not know what JeepHammer knows but he explained to me that all old school vehicles use manifold vacuum and ported vacuum came along with stronger emissions regulations.
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Unread 03-18-2010, 11:08 AM   #12
PINKANDBLACK
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One of the instructions even says to disconnect the plug for the stepper motors and that this stays disconnected from here on out. I tried that and it didnt do anything.
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Unread 03-18-2010, 11:10 AM   #13
PINKANDBLACK
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Setting the timing using a vac gauge sounds awesome. Im going to have to try that.
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Unread 03-18-2010, 11:11 AM   #14
timatoe
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Is it turning over? Is it firing at all?

Forget ALL the wires in the loom, run a new wire from the orange at the distributor to the orange at the ICM and the same for the purple. On my 90 the wire colors were not the same after going through the loom and into the bulkhead and back out.

Start with running two new wires, then you can adjust the distributor back and forth in small increments until it starts (assuming it's firing), then set the timing.
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Unread 03-18-2010, 11:15 AM   #15
Fernando
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Quote:
Originally Posted by PINKANDBLACK View Post

As for the timing, I set it at 10 before I started this whole thing and it was running great. Should I reset it to 8? The instructions say set it to 8 plus or minus 2*.
I believe this is where your problem is. Setting the timing on a carbureted Jeep with the ECM still connected is a different process, which I believe involved accelerating up to 1600 RPM and setting the timing at that engine speed.

If you are not timing it properly then it does not start after the Nutter because you have no ignition advance.

Can someone please chime in as to how to set the timing before the Nutter? I only did it once a long time ago, then I nuttered and installed a Weber and forgot about it.

If no one can chime in then I will look at my manual tonight and post the procedure.
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Quote:
Originally Posted by JeepHammer
I don't mind writing for Fernando because he reads, and re-reads EVERY WORD!... Good to write for someone that actually READS the answer, and takes time to UNDERSTAND what comes back for an answer!
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