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Unread 04-07-2013, 05:16 PM   #1
ad-man
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Losing Power while driving

Talking about my 87 YJ with a 4.2 and manual tranny.

I took the wrangler for a ride the other day and came home on the freeway. It ran great through town, very seldom would I get it to 4th gear on the city streets. So I didn't notice any problems. Had a friend looking it over and he pointed out that I had some vac lines that were not the right type of hose.
So I drove it home on the freeway. Only about 18 miles tops. I noticed that in 5th gear it was losing ground. At first I thought it was just because I was going up a slight hill. Not much of one really , maybe 500' up in a little over 2 miles, So not a real hill.
Today I got up and replaced all the vac line I could see with new line. One piece at a time. I did forget on one line which way the plastic piece was in the line. I am only assuming that it is some kind of valve or regulator. It is the one that is circled on the bottom. Plus I also found one hose that was is not hooked up to anything at all. Now I am no engineer, But I am pretty sure that if they made a fitting for it and put a hose on it, than it is supposed to go somewhere. That is the top circle.
Anyway I got this done and thought I would take it out for a quick ride. I got it back on the highway and now I can't get it above 60 and after about 3 miles it starts slowing down. I have a bikini top on it, so it pretty tough to hear the motor above 35 mph. But I am pretty sure that I am hearing knock from the engine, sort of like floating the valves. I slow down enough that I put it back in 3rd and can get rpms and speed back up, but it drops when I put it in 4th again. Never did get to 5th today.
We got to where we were getting off road and took it a couple of miles down a dirt road. Its got some rough spots so I try to hit it a little harder that I normally would just to see what happens. IT does fine even though I don't think it was going in to 4x4 drive. But that's a whole nother thread.
We get back to pavement and now this thing will not idle. It dies every time I put the clutch in. So we have to start it again at every stop sign. Then I started left foot braking and keeping my right on the gas to keep it going. But even now that it has cooled down, it is still the same way. It was idling fine when we first took off after the hose swap out. So I don't know what the heck happened and why I will not get over 60.
Any thoughts?


vac-hose-001-red.jpg  

Last edited by ad-man; 04-07-2013 at 07:46 PM.. Reason: forgot photo. da
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Unread 04-08-2013, 09:25 AM   #2
Que89YJ
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Bump for the 4.2 peeps.
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Unread 04-08-2013, 11:01 AM   #3
ad-man
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Yeah, i saw in another post you had that i need to look at the iac valve or sensor. Plus i am not getting any temp reading for the engine. I replaced the one i thought it was with one from the junkyard but still no reading on the dash. I need to test the wire to see if is broke somewhere. I think i am thinking of the right one. Its at the back of the head on the drivers side and has one wire to it. But when i look them up on ebay all they have are ones that are 2 wires. I do that sometimes to see what they look like to help find them.
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Unread 04-08-2013, 11:24 AM   #4
zeus87gn
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In the one pic you have there, I can see you still have lots of the original emission control 'junk' on your setup
I'm going to guess you still have the fcty computer hooked up and noone has 'bypassed' it

My best guess would be that the Carter carb is dying and cant keep up with fuel delivery the computer is trying to make it feed
The Carter gets old and leaks vacuum - the engine won't get enough fuel the computer tells the carb to send
The computer adjustment can only go so far

If you don't have to have the emissions equipment, do the bypass, change the carb, remove unwanted emissions equipment, upgrade the ignition, retune for your new setup and you will have a 4.2l to be proud of.

If you do need all that emissions stuff for vehicle inspection, ignore what I just said and fine someone that can fix your carter throttle shaft

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Unread 04-08-2013, 12:15 PM   #5
ad-man
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Yeah, the smog shop was where i was coming back from the other day when it was acting up. I have to smog it every year here in Nevada. We are just to close to California.
Would it be better just to replace the carb all together?
What one should i get?
If its not going to run much better i will have to tow it everywhere when i want to ride and thats nit what i really want to do.
Last night it wouldn't idle long enough for me to get back from the cab to run the throttle by hand
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Unread 04-08-2013, 12:52 PM   #6
Que89YJ
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The nutter bypass is 3 wires and reset the distributor. You were coming back from geting it smogged and it started acting up? Are you sure they didn't tweak it to make it pass? Have you thought about registering your jeep in one of the counties that doesn't require the smog test or is it state wide?
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Unread 04-08-2013, 12:58 PM   #7
NonRubicon
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First thing to do is check whether the engine has been Nuttered. If it has been Nuttered then you should eliminate the unnecessary vacuum lines, then focus on the carb. The Carter BBD is notorious for its idle pickup tubes clogging easily.

If the setup is still running on the computer and you are interested in fixing what you have I suggest you start by checking out this page: Adventures Under the Hood.It is pretty much the best source online for explaining what does what on the 4.2L with the computer controlled Carter BBD. You can find 4.2L vacuum diagrams and a lot more information there.

Where swapping the carb is allowed, plenty of people opt for a non-feedback carb as the setup is much more simplified and easier to troubleshoot.
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Unread 04-08-2013, 01:44 PM   #8
Chrisnvegas
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Clogged idle tubes. Common as a cold. Used to happen to my CJ7. You described exactly what my CJ would do. Die at every stop, not idle ect.

Go to this site, scroll down the page and follow the steps. Your Jeep will be fixed today.

I always fixed the Carter. My Jeep ran great and I could adjust it for high altitude in a minute or so.

Don't nutter it, fix it right.



Easy Fix for Jeep 258 Carter BBD Idle Problem
http://www.jeeptech.com/engine/carter.html
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Unread 04-08-2013, 01:53 PM   #9
ad-man
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Thank you. Since i don't know what "nutted" means i will give the jeeptech a shot first. It makes sense that something would get clogged. I bounced it pretty hard a few times could have knocked some stuff loose. Just about bounced the dogs out the back once. And they are used to it since they ride on the back of the quad.
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Unread 04-08-2013, 07:07 PM   #10
pasinbuy
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Could also be the cat is starting to plug up. Also if you have large tires like 33s on your rig 5th gear is useless due to gearing.
I never use 5th gear it just bogs the motor down and it is hard to go above 60 with my 33 inch tires.
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Unread 04-10-2013, 07:44 AM   #11
ad-man
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I hadn't thought about the tires. I have 32s on it. I was hoping to drive this puppy to work this summer, but not like that on the freeway. I am hoping to clean out the tubes tonight. Downloaded the manual and the how to listed here. So if i get all my stuff done hopefully it will be fixed today.
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Unread 04-10-2013, 09:43 AM   #12
Que89YJ
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This is the Nutter bypass. It eliminates the computer control for the carb by changing 3 wires and retiming:
http://www.jeepforum.com/forum/f12/p...bypass-476720/
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Unread 04-10-2013, 03:06 PM   #13
ad-man
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Thanks. Read that whole thing. I didn't see understand the part of it about adjusting the carb and no one ever did answer the questions about whether it would pass smog after. Still dont feel like i understand enough to clean the idle tubes. But i will read more when i get home and try it
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Unread 04-10-2013, 03:35 PM   #14
Chrisnvegas
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Nutter bypass is the removal of smog equipment and could cause a fail. Also could make it tough to sell unless sold as a "tow away".

Jeeps with the Carter carb left the factory running just fine.

If you don't want to repair the carb you have, consider buying a good replacement. They can be had for under $200.
I am NOT a fan of butchering the harness. If I saw a Jeep with a butchered harness, I would pass on buying it and suspect I am not alone.
My vote is to fix it right.
Then you can drive it to work or drive it to Reno and you won't have to worry every year about whether it will pass smog or not.
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Unread 04-10-2013, 03:59 PM   #15
Que89YJ
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The nutter would not pass smog if modified. It is basically taking back the ignition system to the early CJ ignition system. The nutter on the other hand is a good mod and necessary if you put on anything other then the stock carb and is probably the #1 mod on the 4.2.
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