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Unread 05-23-2013, 01:00 PM   #1
Tyler980
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88 4.2 won't run

I bought an 88 YJ 4.2 straight 6 and I did drive it home... had issues with idle, and no brakes, but the only way I had it running was if it idled at 2k rpms... So, I tried setting timing, and setting idle but when at around 1k it'll just stay there for a few minutes... sputter and die out. So, I then rebuilt the carb, and did a nutter bypass, following the instructions I found on this forum, and I can't get it to start up anymore. Going crazy trying to get this thing going, help? By the way, vacuum lines are all over the place and some are plugged some aren't... I'm very new to working on vehicles.

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Unread 05-26-2013, 07:12 PM   #2
Tom95YJ
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Quote:
Originally Posted by Tyler980
I bought an 88 YJ 4.2 straight 6 and I did drive it home... had issues with idle, and no brakes, but the only way I had it running was if it idled at 2k rpms... So, I tried setting timing, and setting idle but when at around 1k it'll just stay there for a few minutes... sputter and die out. So, I then rebuilt the carb, and did a nutter bypass, following the instructions I found on this forum, and I can't get it to start up anymore. Going crazy trying to get this thing going, help? By the way, vacuum lines are all over the place and some are plugged some aren't... I'm very new to working on vehicles.
No brakes or idle you have a major vacuum issue replace your vac line on he brake booster and on the carb for the choke assembly

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Unread 05-26-2013, 07:34 PM   #3
Tyler980
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Well, I got it running now... just won't stay running... Theres only one brake not working which is passenger side front... which I realize I said no brakes making it seem like all of them, my bad. The stem/piston, not sure what to call it, in the proportioning distribution block isn't giving any fluid, couldn't find one to replace, so going to replace the whole block one of these days. Thinking about putting in a manual choke at this point as well.
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Unread 05-26-2013, 08:51 PM   #4
Tom95YJ
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Quote:
Originally Posted by Tyler980
Well, I got it running now... just won't stay running... Theres only one brake not working which is passenger side front... which I realize I said no brakes making it seem like all of them, my bad. The stem/piston, not sure what to call it, in the proportioning distribution block isn't giving any fluid, couldn't find one to replace, so going to replace the whole block one of these days. Thinking about putting in a manual choke at this point as well.
Before you convert to a manual choke there is a vaccum valve on the side of the carb that faces the valve cover. There is a small vacuum goes that runs from that to the underside of the carb that faces the firewall. Replace that one line. That should get the choke vaccum diaphragm working. Last week my Yj ran great but would not idle. So I started chasing vaccum lines and replaced that one. Between that and adjusting my idle speed screw so the Yj idles at 800 rpm it now idles great

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Unread 05-27-2013, 10:00 AM   #5
superj
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Put up a picture of your engine bay.
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Unread 05-27-2013, 10:11 AM   #6
superj
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Check this out

http://www.jeepforum.com/forum/f12/n...lines-1387106/
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Unread 05-27-2013, 07:55 PM   #7
Tyler980
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Quote:
Originally Posted by Tom95YJ View Post
Before you convert to a manual choke there is a vaccum valve on the side of the carb that faces the valve cover. There is a small vacuum goes that runs from that to the underside of the carb that faces the firewall. Replace that one line. That should get the choke vaccum diaphragm working. Last week my Yj ran great but would not idle. So I started chasing vaccum lines and replaced that one. Between that and adjusting my idle speed screw so the Yj idles at 800 rpm it now idles great

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Do you or could you get a picture of which hose you're speaking of? Even though I've nuttered I've begun just hooking the hoses back up where they were supposed to be, and so far its gotten a little better for starting purposes... it'll idle till I touch gas, then it'll rev up and bog out.
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Unread 05-27-2013, 08:13 PM   #8
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Did you check the link i put up?
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Unread 05-27-2013, 08:27 PM   #9
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You need to eliminate and/or replace all the vacuum lines now and get it over with once and for all. If they are original equipment, they are worn out. Otherwise you will be chasing around problems with them forever and won't ever be able to get it tuned right.

You can eliminate many of them, since they don't do anything now that you have nuttered it. There are many threads and many opinions on just what else is good to eliminate and what you should keep. It doesn't matter that much, but the ones that are left should be replaced if they look like they might be original equipment.
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Unread 05-27-2013, 08:51 PM   #10
Tyler980
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Thanks, I saw the link... Like I've said, I'm pretty new so figuring out what those things are by drawings is pretty difficult for me. If there were a video showing which vacuum lines I need to keep, and which I don't need, would be awesome. Also, I believe its called a vacuum solenoid? Ontop of the engine valve cover, is that still needed after nutter, or no? I've unhooked it and gotten jeep to start, and hooked it up and gotten jeep to start... So I'm unsure. I've tried finding videos of people showing their compartments to attempt to see which hoses they have left.
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Unread 05-27-2013, 08:52 PM   #11
Tyler980
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Also, I'm converting to a manual choke from the electric because of a screw broken off that holds the link on, and the inability to remove it.
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Unread 05-28-2013, 02:57 PM   #12
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After getting manual choke all setup... Still need to remove that screw.
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Unread 05-28-2013, 03:11 PM   #13
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Quote:
Originally Posted by Tyler980 View Post
After getting manual choke all setup... Still need to remove that screw.

Use a drill and EZ-Out.
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Unread 05-28-2013, 06:30 PM   #14
superj
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You are going to have to practice reading wiring diagrams and vacuum diagrams so you can get this down. A yj is almost as basic as you can get so learn on this so you are prepared for future work you would like to do.

Here is an overhead of my engine and a shot showing the line for the brake booster. I have 4x4 and distributor in one line and brakes on the other. All the rest has been removed.



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Unread 05-28-2013, 09:37 PM   #15
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Use this link. http://home.sprynet.com/~dale02/control.htm Lots of pictures.

Don't just rip everything out. Find the things you want to take out one at a time, remove them, and cap off the line. Then do the next thing.
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