TJ hard to start after it is warm

[Jeff 24]

Closest thread I have found is a post by FguyTJ about a hard starting TJ.

My starting problems are similar, but I didn't see a conclusions to his post.
01 TJ, 4.0L, banks header, no cat, fuel cell in the tub with a brand new fuel pump.

On the intial start for the day, the Jeep starts fine. You can hear the pump cycle and it fires right up. After the Jeep has been running for a while and is warm (not necessarily hot - usually 210 - 215 operating temps), and you turn it off, it is hard to restart. When it does start, it tends to run rough for a bit and then clears up and runs fine. If you turn it off and let is set for 30 mins, (cools off ???), it generally starts fine.

Its getting to the point when I'm on the trail that I don't want to turn it off because of the restart issues.

Ideas?? I would appreciate the help.

[Knuckelhead]

Look for the TSB on #3 injector insulator...

[tjdriver]

i did the tsb on mine and it didn't work. i'm gonna do all of the injectors and see if that works.

[Knuckelhead]

Originally Posted by tjdriver

i did the tsb on mine and it didn't work. i'm gonna do all of the injectors and see if that works.

It worked on my 2000 Sport...

[flatlander757]

I did the TSB on mine and it is fixed most of the time... mine will still get heat soaked on the hottest of days.

I just ignore it and when it does start, hit the gas once and the stumbling goes away

[Jeff 24]

Thanks for the info. I will check the injectors. It is an aggravation that I would like to solve.

[merkchop]

How long has it been doing this? Did it start as the weather got hot or any other changes you did to before it started?
It sounds like it may be vapor locking on you.

[OzarksYJ]

Could also possibly be your coil pack getting weak. If after a while it just shuts down at a hot or running idle the coil shorts out when they get weak.
Thats what happened to mine and I changed the coil and no more problems.

[Jeff 24]

Yes, I seem to have more trouble in hot weather. For awhile, I thought the Jeep was getting hot so I've added an electric fan and flushed the radiator, BUT it really never gets over 215 degrees or so. Even if I shut it off and restart it, it's not over heating and puking radiator fluid. How do you correct "vapor locking"???
I really appreciate all the feedback. This will give me several options to correc the problem.

[merkchop]

Where did you install your new fuel pump at?
Since you have the cell if you put in an inline pump and installed it under the hood it is probably the reason and you should be able to relocate it to somewhere a little cooler and closer to the fuel pump. That is one of the good things (about the only one that I can think of) with the pumps inside the fuel tanks, they stay cool.

[Jeff 24]

Fuel pump (new) and sending unit are in the RCI fuel cell. It is a bit of a pain in the fuel cell, but like you said, at least it stays cooler. Fuel cell is mounted behind the front seats.

I have double checked the fuel pump seal, and it seems to be okay.

[tjdriver]

Originally Posted by Knuckelhead

It worked on my 2000 Sport...

didn't work for me.

if i stomp the gas after starting it will go away.

[OkLaHoMaYJ]

I'm experiencing the same problem on my 97 with 4.0L. I also have the RCI fuel cell behind the back seat with the stock TJ fuel pump. When it's in the garage covered by shade it starts up just fine. After I drive it in 90-100* weather it takes a good 10 seconds to start, sometimes a little longer.

What is this TSB everyone speaks of? I believe my coil is fine. Might be something to change soon.

[tjdriver]

here is the link to the thread:

http://www.jeepsunlimited.com/forums...ght=hesitating

and here is the tsb:
--------------------------------------------------------------------------------

Fuel System - Hot Start Misfire/MIL ON/DTC's/Rough Idle

NUMBER: 18-031-03

GROUP: Vehicle Performance

DATE: Sep. 05, 2003

THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 18-027-02, DATED SEPTEMBER 06, 2002, WHICH SHOULD BE REMOVED FROM YOUR FILES. THIS IS A COMPLETE REVISION AND NO ********S HAVE BEEN USED TO HIGHLIGHT REVISIONS.

SUBJECT:
4.0L Rough Engine Idle After Restart Following A Hot Soak

OVERVIEW:

This bulletin involves the installation of a fuel injector insulator sleeve.

MODELS:
2000-2004 (TJ) Wrangler (Domestic and International Markets)
1999-2004 (WJ) Grand Cherokee (Domestic and International Markets)
2001-2004 (WG) Grand Cherokee (International Market)
2000-2001 (XJ) Jeep Cherokee (Domestic and International Markets)

NOTE: This bulletin applies to vehicles equipped with a 4.0L engine (sales code = ERH)

SYMPTOM/CONDITION:

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 (90°F) 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.

DIAGNOSIS:

1. 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

REPAIR PROCEDURE:

1. Cut insulator sleeve, p/n 56028371AA, to make two (2) insulator sleeves about 25-30 mm (1 in.) in length.

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).

[OkLaHoMaYJ]

Does anyone have some pics of this? Mine doesn't rough idle as much as it does with the long key cycles.

[merkchop]

The vapor forming around the #3 injector would be the vapor lock. After the fuel heats up it turns into gas vapor and will not let the fuel get through (locking up the line).
Seen many suggestions at fixing vapor lock on different engines from wrapping the exhaust system to installing vents in the hood, having an electric fan stay running for a while after engine is shut down to old school of placing wooden clothes pins on the metal fuel lines (the heat will travel up the wood and not stay in the line, so they say) to just lifting up the hood.
Luckily for me I have not had this problem on my Jeep so I have only read about what other people have done. Only personal experience with it was on a carburetor gas engine in an early 70's dually. I was young at the time and the owner would just let it sit with the hood up on it while we worked on the hot summer days.

[OkLaHoMaYJ]

That's gotta be what it is. It's really bad when it's around 100* here with high humidity. I'll look into wrapping the injectors with some sort of insulation.

[tjdriver]

ill try 2 get a couple of pics. i just went to the stealership with the part # in the tsb and they ordered for me. got it in a couple of days and it was like $11 total.