I have a 2000 jeep cherokee sport, 4.0 straight 6. I love my jeep more than anything in the world, but for some reason only when it is hot out my jeep after being driven for a little time, stopped and turned off for a few mins, then restarted like running into a store it runs very choppy and will not respond to the gas being touched for around 5-10 seconds. The gas seems to be vaporizing when the car is off. Spark plugs and wiring is good, awhile back I covered a spark plug in some plastic wrap to shield it, and that worked temporarily but when it was really hot outside (above 95 degrees) that did not work and now doesn't work at all. If anybody can solve this, I would be shocked because I have several mechanics scratching their heads, and my father a jeep enthusiast has no idea how to fix it (also one of the many mechanics who have tried and failed). The Rpms are also low when I start the truck after it sitting for a minute or two, and then responds after it gets rid of what appears to be the pre-vaporized gas. Code is "cylinder misfire number 3" please help?
Unsolvable problem.
- Thread starter Robby
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- 2000 jeep cherokee
NickLuzier
New member
jeepgirlsrock
New member
Have you checked your fuel filter? My 99 would do the same thing so on a whim I changed the fuel filter and it was all better. Another time I had the same code throw as you did so I replaced the coil and it would not start. It turned out the new coil bank was no good. I put my old one on and she fired right up, jeeps are a finicky animal 
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jeepgirlsrock
New member
Not the fuel filter. I am sure its the heat in the engine not being able to escape which is pre-heating the injectors... I just am at a loss to fix it. I love it, and I don't want to get rid of it. Only Jeep with this problem.. just had to go for the dark green instead of the red one that was a year older and a little cheaper.. Haha.
JPNinPA
Well-known member
Some tj I think 03 and earlier had A TSB regarding cylinder 3 injector heat shield.
Basically there is a heat shield for cylinder 3 injector that keeps the gas from vapor locking after a long heat soak. You could start with wrapping a tinfoil shield to test the theory. From there get the correct part.
JPNinPA
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Basically there is a heat shield for cylinder 3 injector that keeps the gas from vapor locking after a long heat soak. You could start with wrapping a tinfoil shield to test the theory. From there get the correct part.
JPNinPA
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Last edited:
Had a similar problem with my old Jeep Cj7 '77 years ago. Vapor lock and would stop mid way into driving. Sometimes could start 'er up and the sometimes called for a tow. My mechanics scratched their heads for a very long time. Checked out carburetor, spark plugs, wires, starter, distributor, fuel filter, air filter, etc. They ended up adding a choke. I now open the choke slowly, not all the way, I am able to start it up. Problem solved. Bear in mind these mechanics I go to have 40 years of experience. Something about the about gas getting through to the motor more slowly.
P.S. What about the electronic ignition? I had a Mustang that was diagnosed incorrectly by the dealership because it was stopping etc. No solutions $1500 later and a complete tune-up. Older friend mechanic replaced the electronic ignition and boy did he shake his head. No problems after that. A local gas station even said that there could be a computer problem. Got new computer. NOT. Got the run around to say the least.
Good luck.
Good luck.
NickLuzier
New member
My new coil pack did that. It was arcing out the insulator and the only way I found out was Turning the lights out from under my carport and I seen it arcing. I just took the boot insulator off, stretched the spring a little and it solved my problem. Hope something simple like that for you!! Good luck!!
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Dragon5126
New member
How do you KNOW it isnt the fuel filter??? it absolutely sounds like filter/punp issues as they are mounted IN the TANK as an assembly. at the same time you should drop the tank, and using water (YES WATER) hose it out, and drain its of any sludge and crud, and then throw a gouple gallons of alcohol in it and shake the devil out of it to mix with any residual water left in it . dump it out and set it aside for the alcohol to evap. mean while disconnect the fuel line and back pressure it to blow any crud out of it. pull the injectors and clean them with alcohol and carefully examine them blow out the fuel rail with compressed air. At this point when you reassemble it you should not have any fuel delivery issues since you will have had the fue pump, regulator, and filter in hand for a direct visual inspection and replacement if necessarym as ell as cleaned out all fuel storage and delivery components. all thatis left is the PCM.
jeepgirlsrock
New member
I do not trust those code readers. I do use them with a grain of salt to diagnose my girl if she is having a problem. I have been given the incorrect answer too many times and spent money that I didn't need to. I bought my 99 grand Cherokee from a friend that needed some cash for 2000.00 Hell of a steal only had two owners 145000 mi. I had to take a battery with me to test drive it. Well we put the battery in tried to start her up, she sputtered and coughed and would not idle without me keeping my foot on the gas about medium pressure. I figured hmmm maybe new spark plugs would do the trick. Next evening I go back with plugs. Nope not the problem but did run a little better allowing me to drive her around the block. Now I used to be married to a master mechanic that would make me work on my own car and his race car to boot. I was convinced it was a fuel delivery problem and offered up my money,hoping I wasn't making a huge mistake. I'll tell you what, I never had such a scary ride home. Dang thing died on me pulling out into an intersection, had to take a breath. I got her started and found the sweet spot on the accelerator and limped home. The next day I had my code read, which was exactly the same code you are throwing. I wasn't going to spend a penny more than I needed to so I spent some time online and found out that my girl had a fuel filter/regulator in the tank. Bingo, Bango ! I put the new one in and she purred like a kitten! They are cheap and you should at least give it a try 
the end...of that story 
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the end...of that story 
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JPNinPA
Well-known member
Gang while I agree a fuel filter can cause the sputtering. The filter would not be exclusive warm engines, hot climates or to cylinder 3.
I did mention the TSB and will post up the link as soon as found.
The test is easy and cheap. I think it fits the OP description.
The OP should also be sure to have the correct spark plugs properly gapped.
Cheers
JPNinPA
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I did mention the TSB and will post up the link as soon as found.
The test is easy and cheap. I think it fits the OP description.
The OP should also be sure to have the correct spark plugs properly gapped.
Cheers
JPNinPA
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Last edited:
JPNinPA
Well-known member
TSB 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.
TSB for the cold start rough idle and P0303 code: TSB 18-010-01
JPNinPA
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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.
TSB for the cold start rough idle and P0303 code: TSB 18-010-01
JPNinPA
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JPNinPA
Well-known member
Being it was a TSB you may check with a jeep dealer. They may give it to you. Or install for near free being it is a known TSB. Idk if it could be purchased elsewhere.
JPNinPA
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JPNinPA
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Dragon5126
New member
Actually anything in fuel delivery can cause this symptom Its called vapor lock.
Dragon5126
New member
The code readers are only as good as the user reading them. The code they throw is a symptom not an all out "fix this". Which is why, in the beginning they were specifically priced outside the backyard mechanics price range. now anyone can afford a reader, few kow how to interpet the readings and look just at the code and not what else can cause it.
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