92 yj stumbles and dies 20 sec after cranking - JeepForum.com
 1Likes
Reply
 
LinkBack Thread Tools
post #1 of 48 Old 03-24-2021, 02:01 PM Thread Starter
AWJ
Registered User
 
Join Date: Nov 2011
Posts: 41
92 yj stumbles and dies 20 sec after cranking

92 4.0 standard stumbles and dies after about 20 seconds i have checked and verified tps cps cts manifold sensor map sensor installed new plugs dist cap and rotor and plug wires checked fuel pressure while running its 31 with vac hose hooked up 40 unhooked also replaced the o2 sensor am i missing something any help is apreciated guys

AWJ is offline  
Sponsored Links
Advertisement
 
post #2 of 48 Old 03-25-2021, 11:27 AM
jsawduste
Web Wheeler
2006 YJ Wrangler 
 
Join Date: Jul 2006
Posts: 4,095
try disconnecting and plugging the vac hose to the fuel pressure regulator.


31lbs is low,
jsawduste is offline  
post #3 of 48 Old 03-25-2021, 12:19 PM Thread Starter
AWJ
Registered User
 
Join Date: Nov 2011
Posts: 41
Thanks i unplugged the vacuum line and plugged it and the pressure runs 39psi it still stumbled and died out as though its not getting fuel
AWJ is offline  
 
post #4 of 48 Old 03-25-2021, 12:37 PM
Siva283
Registered User
 
Siva283's Avatar
1993 YJ Wrangler 
 
Join Date: May 2011
Location: Baltimore
Posts: 5,160
Quote:
Originally Posted by AWJ View Post
Thanks i unplugged the vacuum line and plugged it and the pressure runs 39psi it still stumbled and died out as though its not getting fuel
31 psi at idle and 40 with the vac removed is correct. I see a list there but I did not see the crank sensor listed. That causes alot of issues like these.

Is it always the exact same amount of time? A loose or bad ground can cause this too.

When it shuts off will it start right back up? If not is it missing fuel or spark when it is in a no start condition.
Siva283 is offline  
post #5 of 48 Old 03-25-2021, 12:54 PM Thread Starter
AWJ
Registered User
 
Join Date: Nov 2011
Posts: 41
I did check the crank sensor no resistance was seen between post b&c and yes it will crank right back up i cleaned the grounds i knew where where the one on the firewall passenger side and back of the head to firewall i am not sure how the ecm grounds though
AWJ is offline  
post #6 of 48 Old 03-25-2021, 01:08 PM Thread Starter
AWJ
Registered User
 
Join Date: Nov 2011
Posts: 41
Yes it is pretty close 15-30 seconds
AWJ is offline  
post #7 of 48 Old 03-25-2021, 01:47 PM Thread Starter
AWJ
Registered User
 
Join Date: Nov 2011
Posts: 41
The fuel pump thats in it is original my dad bought the jeep new when i was in 7th grade and left it to me i have had it and took good care of it for about 7 years now i did that momentary fuel pressure test where you pinch the return line while pump is running and got 80 psi the gauge climbed slow and the pump sounded like she was bogging down after about 60 psi
AWJ is offline  
post #8 of 48 Old 03-25-2021, 03:19 PM
Flyer58
Registered User
 
Flyer58's Avatar
1992 YJ Wrangler 
 
Join Date: Jul 2019
Location: Magnolia
Posts: 241
Does the fuel pressure drop before or after the engine quits? I know someone with a TJ that has this problem but hasn't had the time to look into it.

The idle speed is controlled by an Idle Air Control valve located on the throttle body. It's a small plunger that slightly opens and closes just enough to maintain a steady idle. That valve can get sticky and gunked up so spraying some cleaner in there may help. The valve may be closing too much and shutting down all airflow.

I'm thinking the initial idle will be slightly higher to get a cold engine running then close down. Can you keep the engine running at 1500 or so after start by using the gas pedal?
Flyer58 is offline  
post #9 of 48 Old 03-25-2021, 06:28 PM Thread Starter
AWJ
Registered User
 
Join Date: Nov 2011
Posts: 41
I put in a new iac and when i crank it the rpms are steady 800 then when it starts cutting out they bounce 800-1250
Flyer58 likes this.
AWJ is offline  
post #10 of 48 Old 03-25-2021, 06:29 PM Thread Starter
AWJ
Registered User
 
Join Date: Nov 2011
Posts: 41
The pressure rises after it quits
AWJ is offline  
post #11 of 48 Old 03-25-2021, 06:31 PM Thread Starter
AWJ
Registered User
 
Join Date: Nov 2011
Posts: 41
And yes when it first cranks it's around 1500 and instantly drops to around 8 or 9 hundred but its warm here in mississippi
AWJ is offline  
post #12 of 48 Old 03-25-2021, 06:34 PM
The_Goob
Web Wheeler
 
The_Goob's Avatar
1991 YJ Wrangler 
 
Join Date: Jun 2012
Location: Walcott
Posts: 4,665
Garage
Possible plugged vent line on top of fuel tank. try with gas cap off and see if any change.
Possible plugged CAT converter(does exhaust stink??)
Oil plugged air filter? these yjs like to puke oil into the air filter

I had a bad coil do this to me before but it was more of a die after a few moments of driving, not stumble.

Just a few suggestions that hadnt already been mentioned


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

YJoTM~April '14~June '15~April '17~July '20

Subscribe to my YouTube!-->
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
The_Goob is offline  
post #13 of 48 Old 03-26-2021, 05:13 AM
Siva283
Registered User
 
Siva283's Avatar
1993 YJ Wrangler 
 
Join Date: May 2011
Location: Baltimore
Posts: 5,160
The fuel pressure rises as it dies?
Siva283 is offline  
post #14 of 48 Old 03-26-2021, 07:58 AM Thread Starter
AWJ
Registered User
 
Join Date: Nov 2011
Posts: 41
I actually have a spare coil i tried that no change the air filter is new i went ahead and dropped the tank and got the part number off the pump its a bosch since its loud and 29 years old i figured i would replace it the new one should be here next wednesday the exaust does not smell Bad but if i wanted to eliminate the cat would i just cut the exaust upstream of the cat and weld it back after i checked to see if it ran or is there another way?
AWJ is offline  
post #15 of 48 Old 03-26-2021, 08:02 AM Thread Starter
AWJ
Registered User
 
Join Date: Nov 2011
Posts: 41
I will check the vent lines today and yes the fuel pressure rises to 39psi when it dies i assume this is due to vac loss on the regulator
AWJ 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











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