Engine dies while driving. Only on bumps - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > TJ Jeep Wrangler Forum > TJ Tech Forum

Join Wrangler Forum Today


Like Tree1Likes
  • 1 Post By Glycerine
Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 05-10-2019, 09:08 PM
Thread Starter
  #1
Newb
 
Join Date: Mar 2011
Posts: 8
Engine dies while driving. Only on bumps

Looking for some pointers from the more knowledgeable on connections to check.

99 TJ 2.5L manual

Symptom: while driving the engine would sidedly die, or occasionally flash a brief CEL and the speedo would nose dive (while at speed), before recovering. Thought it might be fuel pump or CPS. Checked fuel pressure, 50 psi steady for 15 mins at idle. Checked fuel pump connector that I could get to in front of the tank, seems solid. So I go buy a new CPS and pop it in. Test drive the jeep and it almost dies. However i now notice that only when going over sharp bumps at around 25-30mph, this triggers the dying. Almost positive it’s only when the rear axle hits. In hindsight, that matches what I recall from the first few times.

I just had a shop install a ECGS 8.8 rear axle and SYE. It’s been driving fine for 2 weeks. A buddy asked for a refresher course learning manual today. He was a bit less experienced than he claimed. Lot of stalls and jerking, and at one point I heard a horrible drive shaft thump and called it a day. When I’m driving it still rolls fine so I don’t think he did any structural damage.

Given the above, the only thing I can think of is maybe the fuel pump has some sorta intermittent ghost (4 or 5 year old parts store brand, not Bosch), or there’s some electrical connection associated with the transfer case or hidden fuel pump connection that’s loose and being jarred by the bumps. Would the transfer case connections cause the engine to die? Is there some other fuel pump connection I’m missing? Anything else I’ve missed entirely?

Any help would be appreciated. This one has me stumped.

Glycerine is offline   Quote
Old 05-11-2019, 07:05 AM   #2
Jeeper
 
Join Date: Apr 2013
Posts: 12,112
Not fuel pump if gauges affected

Sounds like maybe a intermittent tub ground

Check the ground strap

Look on hinge edge of underside of hood. There should be a ground strap bolted on with other end attached to a firewall bolt

From that same firewall bolt another ground strap is attached and other end goes to a bolt on top back of engine

Check that ground from firewall to engine make sure undamaged and clean and tight on both ends


Sent from my iPhone using Tapatalk

Digger84 is online now   Quote
Old 05-11-2019, 07:10 AM   #3
Jeeper
 
MoabCarl's Avatar
 
Join Date: Jan 2019
Location: Metro Detroit MI
Posts: 299
I had my Jeep turning off randomly on large bumps from a heavy key chain that would literally turn off my Jeep.
__________________

Red Rock 4-Wheelers EJS Trail Gunner
2001 TJ 4.0 Auto
2007 JKU LS3, PR60s, too much to list....
2012 JKUR bone stock
2018 Tacoma TRD Off-Road
MoabCarl is offline   Quote
Sponsored Links
Advertisement
 
Old 05-11-2019, 12:48 PM   #4
Jeeper
 
RUBI 4 MY MRS's Avatar
 
Join Date: Feb 2011
Location: Trails of Nevada
Posts: 3,142
Maybe a long shot here but worth checking.

There is a wiring harness that passes behind the engine with very little clearance between the engine & firewall. The firewall has a bolt from the cab sticking out & the harness can rub on it causing damage. There are several wires in the harness & any of them can randomly get damaged causing any number of problems from blown fuses to loss of power. This often happens either when hitting bumps or sometimes when turning causing the engine to shift enough to push the harness into the bolt.

It is tight & hard to see back there but worth checking it. Here is a link to one such problem.

https://www.wranglerforum.com/f210/bl...l#post15863393

And this with 2 with the same problem & some photos/diagrams. Note posts 6 & 15.

http://www.jeepforum.com/forum/f9/so...needed-2490873
__________________


'05 Rubi TJ Unlimited
'93 Toyota 4Runner
RUBI 4 MY MRS is offline   Quote
Old 05-11-2019, 07:21 PM   #5
Jeeper
 
TheDesertOutlaw's Avatar
 
Join Date: Jan 2012
Location: Riverside, CA
Posts: 2,313
My Jeep would intermittently die when I would hit a bump due to the middle connector to the wiring harness dry rotting and not retaining the connector. A military spec zip tie (3 actually) fixed the problem.
__________________
Tomb Raider #815 RUBICON with 35s
https://scontent-b-sjc.xx.fbcdn.net/hphotos-xpf1/t1.0-9/1517457_10203416408666416_5192773015714389607_n.jp  g
My Soundcloud page
TheDesertOutlaw is offline   Quote
Old 05-12-2019, 04:53 PM
Thread Starter
  #6
Newb
 
Join Date: Mar 2011
Posts: 8
Got some time to play with it today. I didn’t notice anything upon first glance at the firewall connector. I’ll have to take a closer look. That really seems like the likely culprit as I keep throwing parts at the jeep.

I’ve replaced the CPS, VSS, and some of the general tuneup items (cap, rotor, plugs and wires). The jeep began being a little hard starting to where you had to goose it to get it to start. Went to the local store and picked up and IAC ($80!). Popped that in and it started surging and throwing IAC codes. Put the OEM one back in and things were back to the previous state. Returned that IAC and ordered one online for 11 bucks. We’ll see if that helps at all.

I’ll take a closer look at that harness and report back. Given all the start and stopping from my buddy’s learning attempt, I could see something getting rubbed the wrong way
Glycerine is offline   Quote
Old 05-12-2019, 09:12 PM   #7
Jeeper
 
Laggy's Avatar
 
Join Date: Sep 2014
Posts: 3,239
Check main grounds.
Check alternator and fuse box leads.
Fuel pump could do this.
__________________
Laggy's 97 Build Thread

Here it is standing: atoms with consciousness; matter with curiosity. Stands at the sea, wonders at wondering: I, a universe of atoms an atom in the universe. - Richard Feynman
Laggy is offline   Quote
Old 05-16-2019, 10:55 AM
Thread Starter
  #8
Newb
 
Join Date: Mar 2011
Posts: 8
Checked all the main grounds, checked the engine harness, inspected the wiring in the engine bar near anything that could abrade it, nada. Took a quick clamp to squeeze the harness connections together securely, engine still died.

However, I "fixed" it by replacing the IAC. Now why on earth the IAC would kill the engine from a bump, I have no idea. I figure it would just stumble a bit. However, the jeep has not died once in the spots where I was previously able to make it die at will.

So I spent $240 throwing parts at the thing to find out it was a $11 chinese made part that corrected. Will keep an eye on it.
Laggy likes this.
Glycerine is offline   Quote
Old 05-17-2019, 03:33 AM   #9
Jeeper
 
Laggy's Avatar
 
Join Date: Sep 2014
Posts: 3,239
Success

__________________
Laggy's 97 Build Thread

Here it is standing: atoms with consciousness; matter with curiosity. Stands at the sea, wonders at wondering: I, a universe of atoms an atom in the universe. - Richard Feynman
Laggy is offline   Quote
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not 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
I press the brakes while engine is running- engine dies..and more fishwendel2 YJ Tech Forum 15 09-30-2015 08:25 AM
Runs and dies, runs and dies, runs and dies buster01 YJ Tech Forum 7 06-17-2014 08:47 AM
87 4.2 dies only while slowing down blades2ko YJ Tech Forum 6 06-28-2011 06:52 AM
Clunking over bumps, Semi Hard Bumps. Dr. Venture YJ Tech Forum 7 11-05-2010 10:47 AM
Spedo dies and the engine dies when I brake jbhouse2k TJ Tech Forum 4 03-06-2007 07:17 PM





All times are GMT -5. The time now is 06:39 PM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.1
User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.

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