Dying when letting off gas. - 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 03-03-2011, 10:33 AM   #1
Jeeper
 
Join Date: Feb 2011
Posts: 25
Dying when letting off gas.

OK so I just bought an 89 YJ this past weekend. Its got the HEI and a MC2100 on it. It runs pretty good, idles real good all the way down to 5 - 6 hundred RPMs (even lower). Only problem is when I let off the gas after its been up at around 1200 RPMs or so PLUS it dies. Just king of sputters and stalls. But if I let off the gas real slowly and walk it down to idle it will sit there all day no problems. Any ideas? Maybe a vacuum leak? I was thinking about a FPR but the stock fuel system should work well with the MC2100 right? Anyways what do you guys think I should try?

rambo3489 is offline   Quote Quick Reply
Old 03-03-2011, 10:39 AM   #2
Knows a couple things...

WF Supporting Member
 
Jerry Bransford's Avatar
 
Join Date: Nov 2005
Location: Escondido, Calif.
Posts: 30,870
Images: 2
Have you tried cleaning the carb with a good carburetor cleaner? It might be gummed up so the float or float valve is sticking, or a jet is gummed up, which means you will very likely need to at least partially disassemble the carburetor. Idle problems with carburetors always make me think it's probably just gummed up somewhere inside with varnish.

I sent the mods a note to have this thread moved over to the YJ forum since they are more familiar with carburetors. There are no carburetors in the Wrangler TJ and I barely recognize a carburetor any more. In fact, if I never saw a carburetor again I would be very happy.

__________________
When you have a choice, buy American.

Jerry Bransford is online now   Quote Quick Reply
Old 03-03-2011, 10:41 AM   #3
Jeeper
 
Join Date: Feb 2011
Posts: 25
Well where did I post this? I thought it WAS the YJ forum?
rambo3489 is offline   Quote Quick Reply
Old 03-03-2011, 10:42 AM   #4
Jeeper
 
MLaborde's Avatar
 
Join Date: Feb 2011
Location: East Texas
Posts: 427
I'm no mechanic but I'll try to help.

The Idle Air Control valve (IAC) could be bad. I don't know if an 89 YJ has one, though. A quick search gave me this for an 89 YJ instead:
Master Pro Ignition 2ISC1 - Idle Air Control Valve | O'Reilly Auto Parts
MLaborde is offline   Quote Quick Reply
Old 03-03-2011, 11:06 AM   #5
Jeeper
 
Join Date: Feb 2011
Posts: 25
Quote:
Originally Posted by MLaborde View Post
I'm no mechanic but I'll try to help.

The Idle Air Control valve (IAC) could be bad. I don't know if an 89 YJ has one, though. A quick search gave me this for an 89 YJ instead:
Master Pro Ignition 2ISC1 - Idle Air Control Valve | O'Reilly Auto Parts

Yep it says its compatiable. My question is where is it located? I read the description of it and it stated that it is used with the ECM system. If the HEI is on it already dosent that bypass the ECM all together, or am I thinking stupid?
rambo3489 is offline   Quote Quick Reply
Old 03-03-2011, 12:46 PM   #6
Jeeper
 
billytheyj's Avatar
 
Join Date: Aug 2010
Location: Elko, NV
Posts: 1,319
Quote:
Originally Posted by rambo3489

Yep it says its compatiable. My question is where is it located? I read the description of it and it stated that it is used with the ECM system. If the HEI is on it already dosent that bypass the ECM all together, or am I thinking stupid?
No you are not wrong the hei bypasses the ignition control module and the ecm, HEI system is "self contained" well with hei I believe you can then tear out the entire ecm and ignition control module.
__________________
OHHHH BOOOO!!!!!!!!
billytheyj is offline   Quote Quick Reply
Old 03-04-2011, 07:20 AM   #7
Jeeper

WF Supporting Member
 
yoopone's Avatar
 
Join Date: Dec 2010
Location: Suburban Chicago and the UP of Michigan
Posts: 584
Dying when letting off the gas

I have been here. One of my Jeeps is an 89. I changed all the stuff you are thinking of doing to no avail. Like Jerry above said, it is a clogged jet. A good way to prove it is to make sure the car is good and warm and make sure the choke is open all the way. Take the aircleaner off and shine a flashlight down the throat of the carburator at idle. You should see an almost invisible mist of gas coming from the idle jets in the venturi's. If the idle jets are partiallyt clogged, you will see dribbleing of gas into the carb body. It will be obvious. If you are seeing the dribbleing you need to remove the choke butterfly and shaft, then unscrew the jet assembly on top and remove it. A thourough soaking and cleaning and your Jeep will perform like new again when you let off the throttle. Again, the dribbleing will be easy to see. My 89 sits around every winter and I don't drive it much. I have had it for 17 years now so I have had to do this procedure about 3 times over the years.

yoopone 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:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Letting go yjkid95 General Jeep Discussion 14 02-24-2011 06:37 AM
Help with Jerk and Go, Dying at idle blownfanswitch TJ Tech Forum 9 02-14-2009 08:59 PM
Popping noise when letting out clutch 67mustang TJ Tech Forum 1 03-20-2008 09:40 AM
Well the 4 banger is dying...318 swap questions blueroo YJ Tech Forum 8 09-05-2007 08:42 PM


logo carid shop wrangler parts carid fender flares custom wheels store avs deflectors at carid
» Rates
Get low rates on auto insurance in Canada!

» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 08:00 PM.



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