Need some help diagnosing this... - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > YJ Jeep Wrangler Forum > YJ Tech Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 05-09-2014, 03:52 PM   #1
Supporting Member

WF Supporting Member
 
Join Date: Apr 2014
Location: Camp Pendleton, CA
Posts: 35
Need some help diagnosing this...

Hey Everyone, new to the forum. Read many of your posts regarding similar problems and fixes. Unfortunately they are still coming up short. Here is the issue.
87 with the AMC 258 4.2L. Carter 2 BBL Carb, (don't give me crap just yet). Does not have nutter bypass.
What I did:
Replaced the head gasket and all main gaskets there up - Valve Cover, Temp Gasket, Intake and Exhaust Gaskets. Cleaned up the head while I was in there. Removed valves and took the gunk off of the valves since what I saw was probably there since 1987. Installed new value seals and flushed everything out. New serpentine belt. New plugs.
Cleaned carburetor out of dirt and grime. Only thing I removed was the choke plate and the two screws directly below it to blew it out with cleaner. Ensure everything was in place to include the small ball bearing.
Reinstalled everything to spec. Started up on the 2nd turnover. Sounded fine. Checked timing, had to adjust a few degrees.
Instructions I got for the timing through the forum. Plugged vacuum advance from distributor. Set to 1600 RPM and adjust to 9-11 BTDC. Tighten and reconnect lines. Did not jump around at all. Seemed fine.
Drove the jeep to work for the day, seemed fine. Started up next day, didn't make it to the end of the street before it was stalling out. Thought nothing of it and continued, died again. Thought the idle was set to low. Had to start it 3 more times heading back to the house to get another vehicle to head to work.
I have adjusted timing over and over. Checked the carb. Blew it out again. I can get it to idle fine, but the second you push the throttle wide open it dies out. That is the problem.
Could not find any vacuum leak after spraying vacuum lines and intake. It is pulling around 23 inches. Seems normal.
All cylinders have good compression in normal operating ranges.
I am leaning towards the carb since that is all I hear about being the problem.
Prior to replacing the gaskets it ran fine, just leaked oil. Not from the head gasket as it turned out, but what the heck. It has a new one now. Rear Main seal is next.
Any help would be greatly appreciated.

Bryan0129 is offline   Quote Quick Reply
Old 05-09-2014, 04:15 PM   #2
IITYWTMWYBMAB

WF Supporting Member
::WF Administrator::
 
4Jeepn's Avatar
 
Join Date: Apr 2005
Location: Florence, KY
Posts: 10,268
Images: 5
before it dies, does it stumble or just go right to dead? If you increase the rpm's while stopped does it die or only when moving? I would double check the vac lines, and the carb... my CJ would die... unless I had it real high rpms it would die when coming to a stop.. vac line was not all the way hooked up... and fuel metering tubes(looks like two fangs) on the carter needed cleaned.

__________________
79.96.85.00.01.97.00.97.93.97.95.94
CJ.XJ.CJ. TJ. TJ.ZJ. TJ.TJ. ZJ.ZJ.YJ. XJ
4Jeepn is offline   Quote Quick Reply
Old 05-09-2014, 04:29 PM   #3
Supporting Member

WF Supporting Member
 
Join Date: Apr 2014
Location: Camp Pendleton, CA
Posts: 35
If you ease into the throttle it will increase to redline. If you are already at 1500 or above and go wide open, it will do that just fine. But from idle when it is wide open it dies.

The main throat in the carb is clean. I blew everything out with carb cleaner. To include the "fangs" to ensure they weren't obstructed.

I've tried to find a vac leak but I'm out of ideas. I can't find one.

I still get solid sprays out of the carb when pressing throttle.

Thanks
Bryan0129 is offline   Quote Quick Reply
Old 05-09-2014, 04:46 PM   #4
IITYWTMWYBMAB

WF Supporting Member
::WF Administrator::
 
4Jeepn's Avatar
 
Join Date: Apr 2005
Location: Florence, KY
Posts: 10,268
Images: 5
well I am sure some one with better idea's than mine will chime in... wish I had something better to offer.
__________________
79.96.85.00.01.97.00.97.93.97.95.94
CJ.XJ.CJ. TJ. TJ.ZJ. TJ.TJ. ZJ.ZJ.YJ. XJ
4Jeepn is offline   Quote Quick Reply
Old 05-09-2014, 04:48 PM   #5
Supporting Member

WF Supporting Member
 
Join Date: Apr 2014
Location: Camp Pendleton, CA
Posts: 35
No problem. Thanks though
Bryan0129 is offline   Quote Quick Reply
Old 05-09-2014, 05:33 PM   #6
kik
Jeeper
 
kik's Avatar
 
Join Date: Dec 2008
Posts: 4,833
Images: 1
It sounds like your accelerator pump.
kik is offline   Quote Quick Reply
Old 05-09-2014, 05:41 PM   #7
Supporting Member

WF Supporting Member
 
Join Date: Apr 2014
Location: Camp Pendleton, CA
Posts: 35
I thought about that. If I hold the choke plate down I can open it up from idle with no problem.
I read some where to check the accelerator pump to press quickly on throttle when it is off to test and see if fuel comes out when it is off to feed more fuel. It did what test said to do. Unless that was something completely different.
Bryan0129 is offline   Quote Quick Reply
Old 05-09-2014, 05:51 PM   #8
kik
Jeeper
 
kik's Avatar
 
Join Date: Dec 2008
Posts: 4,833
Images: 1
Also make sure your float is correct and not sticking. Both are symptoms of what you're describing.
kik is offline   Quote Quick Reply
Old 05-09-2014, 06:10 PM   #9
Supporting Member

WF Supporting Member
 
Join Date: Apr 2014
Location: Camp Pendleton, CA
Posts: 35
Is there a way to check accelerator pump?
Bryan0129 is offline   Quote Quick Reply
Old 05-09-2014, 06:11 PM   #10
Jeeper
 
Join Date: Feb 2013
Posts: 727
So I have that same engine and setup.

The best way to check your fuel pump is to disconnect in front of the fuel filter right by the carb.

Put a plastic soda bottle over the hose and have some one crank it while you hold the bottle it should pump fuel as it cranks.

Also Chang the fuel filter if you have not already and make sure the vent line goes to the evap can under the washer fluid res.

Lastly the fuel filter lines should be over the top of each other not side by side.

Also take some close up pics we can see things better than describe them.

So if you have not Nuttered yet why did you adjust the timing so far?

Chief
89Saharagreen is offline   Quote Quick Reply
Old 05-09-2014, 06:42 PM   #11
Supporting Member

WF Supporting Member
 
Join Date: Apr 2014
Location: Camp Pendleton, CA
Posts: 35
Quote:
Originally Posted by 89Saharagreen View Post
Lastly the fuel filter lines should be over the top of each other not side by side.

Also take some close up pics we can see things better than describe them.

So if you have not Nuttered yet why did you adjust the timing so far?

Chief
Did not realize that about the fuel filter with lines running on top of each other. I would assume the output that is offset from center goes on top?

Just got back. Will post up some pictures to see if something looks off.

The timing in the manual says to set to that. 9* +/- 2. Is that wrong and where would I find that information. Have not seen anything searching the forum.
Bryan0129 is offline   Quote Quick Reply
Old 05-09-2014, 07:00 PM   #12
Jeeper
 
Join Date: Feb 2013
Posts: 727
So I am not sure what manual you are using I had mine set at 8 BTDC before I switched over to an MC Carb and Nuttered.


It ran fine that way for awhile but I always seemed to have to adjust it.

The issue you are having is common as you probably have read.

If you are set on the carter I would check all hoses for leaks and check all vacum connections.

It honestly sounds like a vac leak.

Pics will help no matter what

Chief
89Saharagreen is offline   Quote Quick Reply
Old 05-09-2014, 07:23 PM   #13
Jeeper
 
Klug's Avatar
 
Join Date: Nov 2013
Location: Ohio
Posts: 294
Klug is offline   Quote Quick Reply
Old 05-09-2014, 07:30 PM   #14
Supporting Member

WF Supporting Member
 
Join Date: Apr 2014
Location: Camp Pendleton, CA
Posts: 35
Flip filter to line up vertically. No difference.
Attached Thumbnails
Click image for larger version

Name:	ForumRunner_20140509_162831.jpg
Views:	33
Size:	111.6 KB
ID:	1081266   Click image for larger version

Name:	ForumRunner_20140509_162849.jpg
Views:	28
Size:	111.9 KB
ID:	1081274  

Click image for larger version

Name:	ForumRunner_20140509_162859.jpg
Views:	29
Size:	100.2 KB
ID:	1081282  
Bryan0129 is offline   Quote Quick Reply
Old 05-09-2014, 11:02 PM   #15
Jeeper
 
Join Date: Aug 2011
Location: north of St.Franisville La.
Posts: 2,388
Send a message via Yahoo to Nubby55
I may be wrong but it looks like you had the fuel line hooked to the Evap can, if so it may be full of gas and causing something bad to happen. IDK
__________________
The Government can not give anything to anybody that it does not first take from someone else !
Nubby55 is offline   Quote Quick Reply
Old 05-10-2014, 12:26 AM   #16
Supporting Member

WF Supporting Member
 
Join Date: Apr 2014
Location: Camp Pendleton, CA
Posts: 35
Quote:
Originally Posted by 89Saharagreen View Post

If you are set on the carter I would check all hoses for leaks and check all vacum connections.

Chief
I am not set on the Carter, I will switch it fairly soon, but I am trying to ensure that the problem is actually the carb first. I don't want to end up ordering the carb and then still have the same problems.

The Weber I was looking at was the Weber 38 DGES along with the fuel regulator to solve the pressure inconsistencies.

I will problem grab some new vacuum hose and replace lines in the morning to eliminate leak issues. Shouldn't take long.
Bryan0129 is offline   Quote Quick Reply
Old 05-10-2014, 06:14 PM   #17
Supporting Member

WF Supporting Member
 
Join Date: Apr 2014
Location: Camp Pendleton, CA
Posts: 35
Quote:
Originally Posted by kik View Post
Also make sure your float is correct and not sticking. Both are symptoms of what you're describing.
Pulled carb off this morning. Cleaned, checked float and other components, and reinstalled.

New symptom though, will only start at higher rpm and now dies at idle. I can keep it running with it over 2K.
Bryan0129 is offline   Quote Quick Reply
Old 05-10-2014, 06:20 PM   #18
kik
Jeeper
 
kik's Avatar
 
Join Date: Dec 2008
Posts: 4,833
Images: 1
Quote:
Originally Posted by Bryan0129 View Post
Pulled carb off this morning. Cleaned, checked float and other components, and reinstalled.

New symptom though, will only start at higher rpm and now dies at idle. I can keep it running with it over 2K.
Sounds like it's time to replace the carb.
kik is offline   Quote Quick Reply
Old 05-10-2014, 07:37 PM   #19
Supporting Member

WF Supporting Member
 
Join Date: Apr 2014
Location: Camp Pendleton, CA
Posts: 35
Ok, slight overlook. Forgot to plug up one of vacuum tube to carb. So forget about the no idle problem.

Main problem still exists. I can get it to idle better now where it is supposed to be around 750. Couldn't do that before.

When timing is at 9 BBC the throttle problem is noticeably bad. When it is up past 16 or so it is there but not as bad.

Probably does help figure out the problem though.

It does spudder at idle though.
Bryan0129 is offline   Quote Quick Reply
Old 05-11-2014, 12:06 PM   #20
Supporting Member

WF Supporting Member
 
Join Date: Apr 2014
Location: Camp Pendleton, CA
Posts: 35
Update:

Timing is set at 9* +/- 2 as per what the manual says and what is under the hood at 1600 rpm with the vacuum advance plugged.

I am replacing all vacuum lines right now, just took a break for a few.

I took it out for a drive, and it drives fine at all RPMs. The only issue is the quick throttle response from idle makes it die. If you ease into it, it runs fine.

Here are my thoughts: (Not an any particular order)

1. The pump is not working properly.

When wide open from idle, it is either getting too much fuel and flooding itself out or it is not getting enough fuel and getting too much air when the carb opens up and killing itself.

I can look in the carb and see good healthy sprays when I hit the throttle and it runs fine at higher RPMS.

2. The carburetor is the problem. Do not know what exactly is wrong with it though.

I am pretty savvy when it comes to figuring out problems, but I cant get wrapped around this one. If someone needs something tested, let me know and I will do what I can. I need to get this back up and running correctly.
Bryan0129 is offline   Quote Quick Reply
Old 05-11-2014, 02:57 PM   #21
Supporting Member

WF Supporting Member
 
Join Date: Apr 2014
Location: Camp Pendleton, CA
Posts: 35
Carburetor ordered. Will update in a few days.

Thanks to all for advice...
Bryan0129 is offline   Quote Quick Reply
Old 05-15-2014, 02:09 AM   #22
Supporting Member

WF Supporting Member
 
Join Date: Apr 2014
Location: Camp Pendleton, CA
Posts: 35
Update. Problem solved. Carburetor was the issue. Go figure. Replaced with weber from Redline. Runs great now.

Thanks all!
Bryan0129 is offline   Quote Quick Reply
Old 05-15-2014, 06:11 PM   #23
Jeeper
 
Join Date: Jan 2013
Location: CA
Posts: 684
Just a heads up - California has very strict smog laws regard what is legal to put on what vehicle.

The only smog legal options for the 1987 4.2L YJ are:
  • Carter BBD in full factory setup (everything there and functional as it was from the factory)
  • Howell TBI (C.A.R.B. approved version)
  • Mopar MPFI (C.A.R.B. approved version)
  • Engine swap to a newer year fuel injected engine (like the 4.0L)
While the weber will do the trick for now to get you rolling again, it won't pass visual for the smog test (and probably wouldn't pass the sniffer either). If you are going to keep it carbed you'll have to put the carter back on for it to pass smog, and you'll have to figure out why the carter is behaving badly. Check out this site for details on the 4.2L setup: Adventures Under the Hood. It has plenty of diagnostic tips and tricks, as well as explains what does what - pretty much the best resource online that covers the factory setup on the 4.2L. The factory 4.2L is a Rube Goldberg dream.

I fought with the factory carter for a year before I finally caved in and went with Howell TBI.

Kinda sucks for us 4.2L owners here in California but that's the laws as they stand.
__________________
1990 Wrangler 4.2L
Howell TBI, 2.5" OME springs; OME Nitroshocks; 5/8" OME shackles; Swaybar discos; 31" tires/15" rims
NonRubicon is offline   Quote Quick Reply
Old 05-15-2014, 07:53 PM   #24
Supporting Member

WF Supporting Member
 
Join Date: Apr 2014
Location: Camp Pendleton, CA
Posts: 35
Yea, got the speech quite a few times. It's registered and tagged for Florida. No laws. Just here temporary on Camp Pendleton.

Thanks for the info too!

Bryan0129 is offline   Quote Quick Reply
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Download our Mobile App

» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 12:40 AM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC