Stalling out

[flxy_tj]

:eek: Ok I have a 97 TJ with a 4.0 liter and a five speed. when the engine is hot and I stop somewhere for a few minutes like 15 to 30 mins. The jeep will start fine and idle but when I give it gas to get going it kind of stumbles like no fuel of ignition. I take my foot off the gas and then get back on the gas and it will run fine. I just put in a new fuel pump and a coil, cap, rotor, and wires. and the plugs have about 6000 miles on them.... any ideas would help. :confused:

[Huck]

Hey i've been reading some service bulletins (referrred to from the Rubiconownersforum.com). There seems to be a heat soak issue with 4.0 litres of late. This issue causes the engine to miss (sounds like what happening to you) after shutting it down for a few minutes. They state its very common after highway driving. One could assume it'llbe a very common problem in the desert heat. I believe they haven't fully gotten a solution worked out yet. The heat soak is referring to the engine block coolant super heating after shutting off the motor. I'll have reread the thread and see if it was causing an issue in the fuel rail. My thinking is that it was and causing a vapor lockish issue. I may be incorrect about this and will try to find a minute to get back to the site. I know that the issue is causing the 4.0's to misfire on one to several cylinders and this, I'll bet, is your problem. Check with your local D/C dealer and see if they are familiar with the service bulletins. I've read them on the D/C service bulletin website. I hope this helps.
Huck

[ROCKFAN]

Hmm - share the info if you find out more. I have been experiencing something very similar on sproadic occaisions with my Rubicon - usually on a trail, after a long crawl section, I'll shut down and take a short break. When I start it up again, it acts like the fuel flow is messed up, with very rough running for a few minutes. Haven't tried shutting it off and starting up again (the Microsoft solution - reboot it:) ) - will try that next time it occurs.

Heat soakback causing vapor lock makes sense given the symptoms I've seen.

[Huck]

Yeah, I found the thread again at the rubiconownersforum.com (if you own one, I recommend the site as a regular stop).
Essentially, I was right after a 10-20 minute period (rest on a hot motor) this heat soak causes a misfire on the third cylinder. This is due to excessive heat build up in the fuel rail, causing it to vaporize the fuel. They say its more pronounced when using fuel with a high ethanol content. (sound familiar, its winter/spring and we run extra ethanol in our "Valley of the Sun" fuel)
Anyway I made a copy of the of the service bulletin and repair recommendation from D/C. I'll credit Chris from the Owner's forum with the copy of the TSB (I believe its short for Technical Service Bulletin)
Here ya go:
The numbers referenced below are the servic bulletin numbers
Posted: Thu Mar 25, 2004 2:14 am Post subject:

--------------------------------------------------------------------------------

OK, I found it. Late night Jeep surfing the web (it's a sickness with no cure).

Here it is.

1803103 - 4.0L ROUGH ENGINE IDLE AFTER RESTART FOLLOWING A HOT SOAK
Date: 09/05/03 (supercedes 1802702 dated 09/06/02)
Model Year(s): 1999-2004
Description: NOTE: This bulletin applies to vehicles equipped with a 4.0L engine. This bulletin involves the installation of a fuel injector insulator sleeve.
Details: Customers may describe a 20 to 30 second rough idle following the restart of a heat soaked engine. This condition may be most noticeable when the engine is restarted following a prior 10 to 20 minute heat soak in hot ambient conditions of approximately 32 C (90ºF) or higher. This condition may be consistent with short city stop-and-go driving trips and can be aggravated by the use of fuel with a high ethanol content. Depending upon various conditions a MIL may occur due to DTC P0303 - Cylinder #3 Misfire.
This condition may be caused by heat from the exhaust manifold that following engine shut down migrates to the area around injector #3 and causes fuel vapor to form within the injector. This in turn may cause a momentary misfire of cylinder #3 until the fuel vapor is cleared of injector #3. The insulator sleeve lowers the injector #3 temperature to a point below which the fuel will not normally vaporize.
If vehicle exhibits a rough idle, and if a misfire of cylinder #3 is observed following a 10 to 20 minute hot soak, perform the Repair Procedure.
Parts required:
56028371AA Ignition Wire Shield
Repair procedure:
1. Cut insulator sleeve, p/n 56028371AA, to make two (2) insulator sleeves about 25-30 mm (1 in.) in length. See diagram.
2. Install one sleeve around injector #3, with the slit on the upward facing side of the injector. Install the other sleeve with the slit on the downward facing side of the injector.
3. Confirm sleeve is flush to intake manifold surface around injector.
4. Check injector #3 wire and ensure that the injector is rotated to a 2 o'clock position (from driver’s side of vehicle).

If you want to see some more of the TSB's:
The TSBs are at:
http://www-odi.nhtsa.dot.gov/cars/problems/tsb/tsbsearch.cfm

Let me know if this helps or just causes anyone more confusion.
HTH
Huck

[ROCKFAN]

Excellent! :D :) :o Armed with this, I will either bug the stealership or just wrap some insulation around the #3 injector...

[flxy_tj]

:)...... Good deal I will try to insulate the fuel rails. That is the problem to a tee. Man thanks alot I really appricate it. I will let you know how it goes. Also if anyone is need of a fuel pump I got mine from pep boys for like $120.00 not bad when compared to dealer cost. I was able to swap it out in like about 2 hours. :D

[Huck]

Hey there Flxy,
I hope this helps with your issue. Hey, are you the white TJ at Perry's? If so, he's helped me many times over with some rebuilds on my old spa. (it cranks these days and he's good honest people) I've seen some of the photos in the shop and thought, Hmmmm.. I wonder if they know I do that stuff too? My Rubi has been parked in front of the shop a few times over the past year or so.
Let me know if it (the repair) works for you guys. We might want to get the info out to some of the other folks, as some type of tech article or something. I don't know what the best way would be.....
Huck

[flxy_tj]

Huck,
Thank you for the help.. I unfortunetly do not know a perry that does spas... I think I have seen you on the sunflower run in jan when it rained, hailed and everything else.
The fix sounds like it will work. I'm going to fab up a heat shield out of scrap metal I got laying around, I'm going to make it hopefull protect the whole fuel rail.... we will see how it goes. I am almost positive that is the problem, I just have never experinced vapor lock on a injected rig... :confused:
I'm going on a sunflower run on the forth of april with arizona backcountry again. Also I will keep you posted on the fab process. maybe we can up with a cheap solution for people to do themselves...... :D
Let me know if you need anything. Talk to you later.

Flxy A.K.A
Jon Snowden :rolleyes:

[Y2K-XJ]

What kind of insulation are you guys using? I dont have the misfire but I like to stay on top of any TSB's .. I have a 2000 xj W/ 4.0

[flxy_tj]

:D .....I have not figured out exactly what I'm going to use yet I might make a shield out of some scrap metal I got laying around or find some type of insulating material like header wrap or something to help it out. I will let everyone know when I get it figured all out...... If it all goes well it will be cheap and easy to do, also it has to work..... :cool:

See you on the trail ....... Jon Snowden

[ROCKFAN]

This weekend I took a square of plain old aluminum foil, folded it over 5-6 times to make a strip about 2" wide, and wrapped that around the #3 injector - if you read the TSB, all they are doing is insulating the body of the injector. On my 03 Rubi, there is a heat shield there already between the intake manifold and the injector rail, but I can see where there may be a heat leak coming through. Ran FR42 this weekend with no return of the misfire problem, but it was not that warm out. It will probably take a few more runs into the hot weather before I have convinced myself that the problem is solved, but I have high hopes :)

[Huck]

After reading your reply, I do remember you from the giant run up to the mine. A fun messy day it was.... I was wondering about Perry's because there is always a white TJ with the license plate FLXYTJ parked out front. I thought I was smart and had put 2 and 2 together. Obviously not... Oh well, just don't blame me for trying. I hope the repairs/wrapping of a heat shielding substance works for you guys. Do keep me posted as things start to heat up.
Be well,
Huck

[flxy_tj]

ok will do have not really had time to mess with it. Was to busy re-wiring my rock lights and what not to a main panel... :D There is another sunflower run this weekend on sunday, with Arizona Backcountry. I'll be going on that. Talk to you later.
Snowden...