TJ - Starts Fine When Cold; Won't When Hot - JeepForum.com
 
LinkBack Thread Tools
post #1 of 8 Old 09-04-2019, 04:18 PM Thread Starter
TJdontDIE
Registered User
 
Join Date: Sep 2019
Posts: 4
TJ - Starts Fine When Cold; Won't When Hot

My Jeep has been sitting for a year and I recently got it running again. The Jeep runs great besides the hot startup. The jeep will fire right up when cold but won't start if it is hot. Once the jeep cools off it will start right back up. I think this is because of a fuel problem most likely from the ethanol gas sitting for a year and gumming something up. I can only think that everything is open and clear when it starts and after running the fuel buildup clogs something like the fuel injectors. Then after sitting the debris settles allowing for a fresh startup. Does this sound correct? New Fuel Injectors??

I have tried running Gum OUt and Sea Foam which generally helps the engine run smoother but isn't helping on the startup.

TJdontDIE is offline  
Sponsored Links
Advertisement
 
post #2 of 8 Old 09-04-2019, 04:34 PM
jtec
Registered User
2014 JK Wrangler 
 
Join Date: Oct 2017
Posts: 6,303
I am not sure what MY (model year) and or engine trans.
lets start simple easy things first -
Try to check for codes - don't know till we look. post ALL codes if any.

Fuel pressure would be a great place to start.
Attach gauge, turn key to RUN (not start) observe fuel pressure copy high reading, leave in RUN record fuel pressure in 5 min post that pressure.

Any issue with temp gauge ?

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
jtec is offline  
post #3 of 8 Old 09-04-2019, 04:38 PM
jtec
Registered User
2014 JK Wrangler 
 
Join Date: Oct 2017
Posts: 6,303
Want To add heat soak can be an isssue vapor lock BUT what MY and what ambients are you dealing with - new england or desert SW makes a differance...

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
jtec is offline  
 
post #4 of 8 Old 09-05-2019, 06:54 PM Thread Starter
TJdontDIE
Registered User
 
Join Date: Sep 2019
Posts: 4
I replaced the fuel injectors today and it initially ran horrible. I think the jeep had to find the timing for the new fuel injectors or the pressure or something. Drove it once around the block and sputtered the whole time. Waited and drove again and this time it drove smooth up til about 2000 RPM so I got some premium gas. Waited and drove more and seemed to keep running smoother. Also seemed to fire up after getting hot. Will check tomorrow to verify but I think I fixed the issue.

PS - The fuel pressure was originally checked as well. It is really easy to do with the release valve on the fuel rail.
TJdontDIE is offline  
post #5 of 8 Old 09-06-2019, 08:53 AM Thread Starter
TJdontDIE
Registered User
 
Join Date: Sep 2019
Posts: 4
Nevermind….. Didn't start today after it was acting fine yesterday. ONce again it started right up and ran great and then I let it sit there for a few minutes and it wouldn't start back up. Guessing if I go pick it up in an hour it will fire right up.
TJdontDIE is offline  
post #6 of 8 Old 09-06-2019, 09:12 AM
bobjp
Registered User
1997 TJ Wrangler 
 
Join Date: Aug 2005
Posts: 2,203
Year? Engine?


The first step in a no start condition is to determine if you have fuel and spark. Did you check fuel pressure when it wasn't starting or when it was? Pull out a plug or put an old one in a wire and see if it sparks when it's not starting.


Any effort at this time beyond checking fuel and spark is a shot in the dark.

97 TJ sport.
bobjp is offline  
post #7 of 8 Old 09-08-2019, 09:28 AM
Deltacottonboy
Registered User
1997 TJ Wrangler 
 
Join Date: Aug 2018
Posts: 33
This sounds similar to a bad upstream 02 sensor. The sputtering and bucking is very similar to mine. From my understanding, the upstream sensor doesn't start relaying back to the computer until the motor is up to temp. This may explain the cold start.
Deltacottonboy is offline  
post #8 of 8 Old 09-08-2019, 02:19 PM
jr03
Registered User
2003 TJ Wrangler 
 
Join Date: Jun 2010
Location: florida
Posts: 497
A bad evap solenoid will leak thru when hot and flood the intake causing hard starting once hot. The purge valve maybe bad or stuck or have some charcoal in it from the vapor canister. Seen two vehicles with hard hot start issues from evap purge solenoid.
jr03 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