Jeep sometimes does not start or starts up then dies?? - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Cherokee & Comanche Forums > XJ Cherokee Technical Forum > Jeep sometimes does not start or starts up then dies??

NEW!! HMF 50"-52" light bar mounting brackets!! SPARTAN LOCKERS are on sale BIG TIME at ROCKRIDGE 4WD!Rubicon express discounts from oconee off-road

Reply
Unread 12-26-2011, 09:44 PM   #1
ChiJeep
Registered User
 
Join Date: Nov 2011
Posts: 32
Jeep sometimes does not start or starts up then dies??

I have a 96 jeep cherokee xj sport. From the day I bought it from time to time it will either not start the first time when I turn the key or sometimes it will start and then idles down and dies. This happens to me atleast 2-3 times a day.

Sometimes it will start right up with no problem, other times it will take 2-3 tries before it gets going, and now i'll start it up it'll idle and then dies.

Never left me stranded but it seems to me that it may be a fuel issue and i'd like to get it fixed.

Sparkplugs were replaced about a week ago.

Any ideas?? Bad injector? Dirty Lines? Both?

ChiJeep is offline   Reply With Quote Quick reply to this message
Unread 12-26-2011, 10:32 PM   #2
TallyZJ
Registered User
1996 ZJ 
 
Join Date: Nov 2008
Location: Tallahassee, Florida
Posts: 1,140
Quote:
Originally Posted by ChiJeep View Post

Any ideas??
What you describe could be any number of single things or a combination of a lot of things.

Instead of guessing or tossing parts at it try to get some real diagnosis done.

- Do you have any check engine lights/service engine lights on now?
- Have it scanned for history codes
- Recently replaced fuel filter?
- Check fuel pressure at the fuel rail with engine running
__________________
1996 Jeep Grand Cherokee Laredo 4x4 - 4.0L
Capital City Jeepers
Build Thread Here
TallyZJ is offline   Reply With Quote Quick reply to this message
Unread 12-26-2011, 10:34 PM   #3
Reptile
Web Wheeler
1991 XJ Cherokee 
 
Join Date: Feb 2011
Location: Bakersfield, CA
Posts: 1,297
Could be a fuel issue but start with cleaning the IAC.
Reptile is offline   Reply With Quote Quick reply to this message
Unread 12-27-2011, 12:13 AM   #4
ChiJeep
Registered User
 
Join Date: Nov 2011
Posts: 32
Quote:
Originally Posted by TallyZJ View Post
What you describe could be any number of single things or a combination of a lot of things.

Instead of guessing or tossing parts at it try to get some real diagnosis done.

- Do you have any check engine lights/service engine lights on now?
- Have it scanned for history codes
- Recently replaced fuel filter?
- Check fuel pressure at the fuel rail with engine running
At the moment I do have a check engine light on. When I purchased the vehicle it did not have a code but one of the nights I was driving it the OEM muffler actually cracked off and was left hanging disconnected from the cat and at that point threw the code PO420 which is a cat failure code. I replaced the muffler and welded in a straight pipe because I liked the rumble the 4.0L gave off. The code disappeared for awhile but it returned recently but I did not check if it was the same code or if it changed to a different problem. I did not have it checked yet because I figured if its the cat or the o2 sensor then I can wait and it does not have to be a immediate fix.

Only reason I feel a scan wouldnt find the issue is because it was dieing out on me when I purchased the vehicle before any of the P0420 codes but I figured it was a quick fix (sparkplugs, coils, etc).

Not sure how old the fuel filter is or when it was replaced last. I only own the car for about 3 weeks.

I'll check the fuel pressure tomorrow morning.

Thanks for your input :]

Quote:
Originally Posted by Reptile View Post
Could be a fuel issue but start with cleaning the IAC.
Do you have a recommendation to clean the IAC with? Im new to the jeep world so I dont know what works best yet.

Brake cleaner, Carb Cleaner, CRC? Doesnt matter?
ChiJeep is offline   Reply With Quote Quick reply to this message
Unread 12-27-2011, 04:00 AM   #5
tjwalker
It's the crank sensor!
 
tjwalker's Avatar
1999 XJ Cherokee 
 
Join Date: Nov 2007
Location: Central Minnesota, MN
Posts: 8,472
Pull the codes. Never ignore a check engine light; it may or may not be related to your current symptoms, but there is only one way to find out.

I'd also get a converter back on there and then you won't have to worry about being in a situation like you are in now with a setup that is guaranteed to screw with your OBD system. Removing the converter buys you literally nothing.

More on cleaning the throttle body and idle air control below.
------------------------------------------------

The Idle Air Control (IAC) is mounted on the back of the throttle body. The valve controls the idle speed of the engine by controlling the amount of air flowing through the air control passage. It consists of a stepper motor that moves a pintle shaped plunger in and out of the air control passage. When the valve plunger is moved in, the air control passage flows more air which raises the idle speed. When the valve plunger is moved out, the air control passage flows less air which lowers the idle speed. Over time and miles, the IAC can get carboned up which can have an adverse affect on idle quality. Cleaning the IAC may restore proper function and is an easy procedure to perform and good preventive maintenance so it is never a bad idea.

CLEANING THE JEEP 4.0 IDLE AIR CONTROL

Remove the air filter cover, associated hoses and the rubber boot that goes from the air filter cover to the throttle body. Remove the IAC with a torx driver (2 bolts; one can be kind of hard to get to)

“Gently” wiggle out the IAC from the throttle body. Gasket on the IAC can be re-used if it is not damaged

Clean the IAC with a spray can of throttle body cleaner; inexpensive and available at any place that sells auto parts. Throttle body cleaner is recommended rather than carburetor cleaner as it is less harsh, safe for throttle body coatings and is best for this task. Use cleaner, a rag and a toothbrush and or Q-Tips. Be gentle; don’t twist or pull on the pintle that protrudes from the IAC as it is fragile and you could damage it.

Thoroughly spray clean and flush where the IAC seats in the throttle body with the same spray cleaner

It is also a good idea to clean the entire throttle body itself, the butterfly valve inside of the throttle body and all associated linkage as long as you have things disassembled

Reinstall IAC and check idle quality
__________________
99 Cherokee, 4.0 AW4, NP242
Past Jeeps: 49 Willys, 81 Scrambler, 88 Comanche
Without "data", all you have is an opinion!
tjwalker is offline   Reply With Quote Quick reply to this message
Unread 12-27-2011, 05:58 PM   #6
TallyZJ
Registered User
1996 ZJ 
 
Join Date: Nov 2008
Location: Tallahassee, Florida
Posts: 1,140
Quote:
Originally Posted by ChiJeep View Post
I did not have it checked yet because I figured if its the cat or the o2 sensor then I can wait and it does not have to be a immediate fix.
A failed cat can ruin your engine and can cause your Jeep to burn to the ground. Should not ignore this. A failed O2 sensor will eventually cause ruin to the cat. Nothing about either of these that should be ignored.
__________________
1996 Jeep Grand Cherokee Laredo 4x4 - 4.0L
Capital City Jeepers
Build Thread Here
TallyZJ is offline   Reply With Quote Quick reply to this message
Unread 01-15-2012, 02:08 PM   #7
ChiJeep
Registered User
 
Join Date: Nov 2011
Posts: 32
Well a little update.

-I replaced my cat and o2 sensor.(Check engine light went away and no codes appear)
-Seafoamed the crankcase, gastank, and through the brake booster line.
-New spark plug wires
-New Fuel Filter
-Cleaned the IAC and Throttle Body (Spotless)

My engine idle is gone and it runs nice and quiet but it still has difficulty starting sometimes. I was going to suggest the cold making it difficult but sometimes it will still have a warm engine after I stepped out for two minutes and it still is hard to start up. Any other suggestions?
ChiJeep is offline   Reply With Quote Quick reply to this message
Unread 01-15-2012, 02:40 PM   #8
Reptile
Web Wheeler
1991 XJ Cherokee 
 
Join Date: Feb 2011
Location: Bakersfield, CA
Posts: 1,297
Heat sink is a common issue on the 4.0. But if it's happening regardless of warm/cold, could be the fuel pump check valve.
Reptile is offline   Reply With Quote Quick reply to this message
Unread 01-15-2012, 02:53 PM   #9
TallyZJ
Registered User
1996 ZJ 
 
Join Date: Nov 2008
Location: Tallahassee, Florida
Posts: 1,140
Quote:
Originally Posted by ChiJeep View Post
Any other suggestions?
Next time you go to start it up cycle the key switch to "On" then "Off" then "On". Do this three or four times then attempt to start. If it fires right up you have a fuel pressure regulator/check valve issue allowing fuel pressure to bleed down quickly.
__________________
1996 Jeep Grand Cherokee Laredo 4x4 - 4.0L
Capital City Jeepers
Build Thread Here
TallyZJ is offline   Reply With Quote Quick reply to this message
Unread 03-03-2012, 07:22 PM   #10
ChiJeep
Registered User
 
Join Date: Nov 2011
Posts: 32
Quote:
Originally Posted by TallyZJ View Post
Next time you go to start it up cycle the key switch to "On" then "Off" then "On". Do this three or four times then attempt to start. If it fires right up you have a fuel pressure regulator/check valve issue allowing fuel pressure to bleed down quickly.
Tried it and it still has difficulty. Anything else I could try? Maybe the CPS?
ChiJeep is offline   Reply With Quote Quick reply to this message
Unread 03-04-2012, 05:57 AM   #11
tjwalker
It's the crank sensor!
 
tjwalker's Avatar
1999 XJ Cherokee 
 
Join Date: Nov 2007
Location: Central Minnesota, MN
Posts: 8,472
You really should start with verifying fuel pressure. For a 96, you should have 49 psi, plus or minus 5 psi. Gotta use a gauge; anything less is guesswork.

Some troubleshooting tips for extended crank times:

Hook up fuel pressure gauge on the schrader valve on the fuel rail

Start engine and bring to normal operating temperature.

Observe test gauge. Normal operating pressure should be 49.2 psi (plus or minus 5 psi)

Shut engine off.

Pressure should not fall below 30 psi for five minutes.

If pressure falls below 30 psi, it must be determined if a fuel injector, the check valve within the
fuel pump module, or a fuel tube/line is leaking. An adaptor tool/hose included with the fuel pressure gauge can help you with this. Consult gauge manual for more information on this but here is basically how it works:

*Turn the engine off and immediately clamp the fuel line at the adaptor hose. Watch the pressure gauge and see how long it takes to lose pressure.

*If the pressure remains at 49 psi for an extended period of time then the problem is in the tank - possibly the check valve. You can limp a check valve problem along indefinitely if you wish as it doesn't mean the fuel pump is going to fail.

If the pressure falls below 49 psi fairly rapidly then the problem is probably a leaky fuel injector. A leaky injector will usually result in some "stumbling" of the engine upon restart as the engine has to burn off the excess fuel.

Good luck; hope this helps. Keep us updated!
__________________
99 Cherokee, 4.0 AW4, NP242
Past Jeeps: 49 Willys, 81 Scrambler, 88 Comanche
Without "data", all you have is an opinion!
tjwalker is offline   Reply With Quote Quick reply to this message
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.
Note: All free e-mails have been banned due to mis-use. (Yahoo, Gmail, Hotmail, etc.)
Don't have a non-free e-mail address? Click here for a solution: Manual Account Creation
Email Address:

Log-in

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.


Thread Tools


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.