Jeep Wrangler Forum - Reply to Topic
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > YJ Jeep Wrangler Forum > YJ Tech Forum > 4.0 Hard Start / Backfire / Rough Run after extended idle

Join Wrangler Forum Today

Thread: 4.0 Hard Start / Backfire / Rough Run after extended idle Reply to Thread
Post Icons
You may choose an icon for your message from the following list:

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:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:


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.

Additional Options
Miscellaneous Options

Topic Review (Newest First)
12-29-2009 07:49 PM
anklenawer pretty simular problem here - my 87 4.2l... just got it running 9 timing was off) we got it to idle perfect - but when you accelerate standing still, its a little hesitant but makes its way up the RPM's .. not sure what it is.. when you drive it ( vehicle weight and uphil) its really hard to do without it sputtering and farting up and down the street - but if you gently accelerate.. its ok - ...

i thought of timing chain, TPS, Fuel pump/filter...and - car issues -

any luck with yours - check out my thread - search for my thread by my name - anklenawer obvoiusly..

good luck
09-16-2009 05:04 PM
4.0 Hard Start / Backfire / Rough Run after extended idle

Suddenly it takes 3-4 (sometimes 5, 6 or 7!) attempts to get it started.

It'll FINALLY sputter, sluggishly and with a rough deep idle, into starting.

Then completely runs fine.

Then, while at red lights, if I don't continually work the gas pedal, when I start to go, it sputters and runs VERY roughly for 10 -15 seconds, then back to 100% normal.

A couple of times, I've tried pumping the gas pedal a bunch (thinking it wasn't getting gas due to a bad pump) and then, when it finally starts - it backfires INCREDIBLY loudly, like a gun shot.

ANY ideas?


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

All times are GMT -5. The time now is 07:08 AM.

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