1997 TJ Running Issues

jeeptjadv

jeeptjadv

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Joined
Jan 14, 2024
Messages
12
Location
Raymond, MS.
Needing some (a lot) of help chasing down running issues on my 1997 Jeep TJ 4.0 Auto with 160,000ish miles.
Short version is when it’s running, it runs great … right now it just doesn’t run longer than about 5-15 minutes

Cranks and runs for 5 to 15 minutes. Most of the time it cranks right back up and does the same thing over and over.
No engine codes on display when key is cycled 5 times
No check engine light on

What I do know …
Battery Voltage 13.2
Battery Voltage while engine running 13.9 with lights/blower on
No voltage drop on meter before engine dies.
Fuel pressure 55ish when running but does leak down after engine dies. Down to 0 in 5ish minutes.
Fuel pump relay seems to stay engaged until engine dies, then drops out in 2-3 seconds.
No drop in fuel pressure when engine dies.
New Wranglerfix PCM
Crank Sensor new x 2
TBS Sensor new (mopar)
Idle Air Controller Sensor
Distributor Ignition Pickup

Cleaned grounds with wire wheel/brush and applied dielectric grease
(2 on fire wall, 2 on engine, 1 on hood, 1 beside coil, 1 on frame from coil)

All sensors are either NAPA or Standard brand I believe.

Have swapped PCM's ... no change in anything.

Thanks in advance for any and all help
Steve

The boys want there jeep back to go riding :)

IMG_0802.jpeg
 
Last edited:
Have your cat checked. I had that problem in my '97 Wrangler and the problem was my Cat. They were recalled for this problem. You, or your P.O. may have missed that recall. An exhaust analysis during a smog check might help to diagnose the problem too. Tap the cat with a rubber mallet. If you hear broken glass, then the Cat is your problem.
 
You can check the cat by taking out your O2 sensors.

Did you clean your IAC? Not just replace it?

Any way to read live data?

-Mac
 
How's the cap and rotor look?

Might want to get a spark plug light on one of the plugs and maybe a noid light on an injector...least then you'd know what was shutting down.

-Mac
 
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Got a spark plug light, and a noid light for the injectors ... Also pick up a cap and rotor.
Lets see what happens in the morning :unsure:

I'm by no means a mechanic at all ... but I can follow simple directions and do have a meter.
 
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Update ...
Maybe not the smartest move but I decided to start fresh from a known baseline and work from there.
This morning I replaced ... All Standard brand sensors/parts. My sad story about my Jeep and not being able to take the dogs riding got me a discount at O'Reilly's :)

*Crank Senor
*Distributor Cap
*Rotor
*Coil Pickup
*Inj Coil
*TBS
*IAS
*MAP

I removed the throttle body and cleaned everything up really good before installing the TBS, IAS, and MAP sensors.

The jeep went from not running more than 3 to 5 minutes, to running great and idling good.
Drove it around the small town I live in, no issues what so ever.
I'll report back this next week after some longer test drives.
 
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