cj 4.2 runs on 3 cylinders? - JeepForum.com

 
LinkBack Thread Tools
post #1 of 11 Old 06-20-2013, 08:23 PM Thread Starter
ROTTEN
Registered User
1994 YJ Wrangler 
 
Join Date: May 2011
Location: SGF
Posts: 768
cj 4.2 runs on 3 cylinders?

My father in law had me post a question for the cj guys.

4.2 with weber carb. Jeep starts but runs on 3 cylinders. There is spark on the 3 wires. Intake is clear. Compression was high,140 in each of the 3 cylinders. Were talking the back 3. Anyone else have this issue? I can answer questions

68 cj5
Rebuilt 4.2
New weber carb


I'm new
ROTTEN is offline  
Sponsored Links
Advertisement
 
post #2 of 11 Old 06-20-2013, 08:35 PM
skizriz
Registered User
1978 CJ7 
 
Join Date: Jun 2011
Location: Scottdale
Posts: 5,311
I assume you put in new plugs, wires, cap and rotor??
skizriz is offline  
post #3 of 11 Old 06-20-2013, 08:52 PM Thread Starter
ROTTEN
Registered User
1994 YJ Wrangler 
 
Join Date: May 2011
Location: SGF
Posts: 768
Of course. New distributor as well. Plugs are the correct gap. Spark was tested with a spark tester on every wire. Timing was verified also.
Valves are opening and closing. Carb has the correct spacers.

I'm new
ROTTEN is offline  
post #4 of 11 Old 06-20-2013, 10:05 PM
petey156
Registered User
1977 CJ5 
 
Join Date: Sep 2005
Posts: 886
Ok. Is the intake a dual plane? Where one of the barrels feeds 3 cylinders, and the 2nd barrel feeds the other 3 cylinders?
petey156 is offline  
post #5 of 11 Old 06-20-2013, 10:40 PM Thread Starter
ROTTEN
Registered User
1994 YJ Wrangler 
 
Join Date: May 2011
Location: SGF
Posts: 768
That I will have to find out. Anything else I should ask about?
What if it is a dual plane?

I'm new
ROTTEN is offline  
post #6 of 11 Old 06-21-2013, 08:20 PM
gosupes
Registered User
1986 CJ7 
 
Join Date: Jun 2004
Location: Monroe
Posts: 1,620
Quote:
Originally Posted by ROTTEN View Post
That I will have to find out. Anything else I should ask about?
What if it is a dual plane?
I don't think a dual plane manifold would make a difference on why the back 3 cylinders are lacking fuel. If spark is there and the timing order is correct, look towards the carb and how it's set up. Are the plugs even wet?

1986 CJ7, 4.2 w/4.0 head, TFI-HEI hybrid ignition, Clifford manifold w/Holley 390 w/cold air intake, OBA, 4.5" lift, Woody CV shaft and Tattons in front, 4.10 gears - lunchbox in front, Truetrac in the back, twin-sticked, blower upgrade for running topless, trying to keep it simple.

It's just a Jeep, and if you don't wheel it once in a while, it's not even that.
gosupes is offline  
post #7 of 11 Old 06-21-2013, 08:55 PM Thread Starter
ROTTEN
Registered User
1994 YJ Wrangler 
 
Join Date: May 2011
Location: SGF
Posts: 768
Single plan oem intake
Also he said its a ford setup. So he is going to try a points system and coil

He said the carb is clean and correct.

I'm new
ROTTEN is offline  
post #8 of 11 Old 06-21-2013, 10:20 PM
petey156
Registered User
1977 CJ5 
 
Join Date: Sep 2005
Posts: 886
How did he identify that the 3 cylinders are not firing? Any chance there is a larger vacum leak near those 3 cylinders?
petey156 is offline  
post #9 of 11 Old 06-21-2013, 10:25 PM Thread Starter
ROTTEN
Registered User
1994 YJ Wrangler 
 
Join Date: May 2011
Location: SGF
Posts: 768
It ran rough at idle well barely idle. Started pulling wiress to find which cylinder was a misfire. Found no change when the back three were unplugged

I'm new
ROTTEN is offline  
post #10 of 11 Old 06-21-2013, 10:26 PM Thread Starter
ROTTEN
Registered User
1994 YJ Wrangler 
 
Join Date: May 2011
Location: SGF
Posts: 768
They went through and replaced all the vacuum lines and verified they were connected.

I'm new
ROTTEN is offline  
post #11 of 11 Old 06-22-2013, 06:19 AM
gmakra
Registered User
1985 CJ7 
 
Join Date: Jun 2008
Location: Chicago area
Posts: 3,560
Could your dizzy be 180 out?
gmakra is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com 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 e-mail address for yourself.



Email Address:
OR

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.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



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 On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome