Jeep will not stay running..not balast resist.

I just picked up a 91 XJ limited. When I try to start it, it will prime the injectors and fire, but after about 5 seconds, it will just die. It will do this as many times as I want it to, but it will never stay running. Any info you could give would be great. I checked the codes, and the only codes that come up are 12 and 55, which do not have anything to do with running, just that I disconnected the battery and that it is finished. It had a cracked ballast resitor and I replaced that, but it will still not stay running. The fuel pump primes, so I am assuming that it is not the fuel pump. Any info would be great.
Brian

P.S. Thank you to all that replied to this thread before.

I've read the other posts to your question ... I'd have to guess it is a fuel problem too. Seems to me if it was ignition, electrical, or computer, it would show up on your codes. If it were mine, I'd double check everthing on the fuel delivery system.

Sorry ... not much help.

Les

Probably a dumb question, but are you sure that the security system is off. That is exactly what my ’91 limited does when the security system has been tripped. Runs for a couple of seconds and then shuts itself off. If it is the security system you can shut it off by manually cycling the drivers side door lock with the key. If that doesn’t work, do the same thing with the hatch lock. The security system will rest itself and shut down the vehicle every time you disconnect and reconnect the battery (at least mine does). PS Does anybody know how to disable that POS system?

Check the air filter? If it's soaked in oil, like many are, it won't stay running.


SimpleXJ

I've also been told that a plugged exhaust (Ie. potato shove in the tailpipe) will do the same thing. Try bypassing the ballast resistor, maybe the new one is bad. You could also try chasing the wires for that, Maybe one is bad, or broken. Bypass the resistor by connecting both the wires together. This will send full voltage to the pump constantly instead of reduced. If it then runs it's a faulty new resistor.

Nobody said

Nobody mentioned the fuel filter........didthey?

Could possibly be a flakey CPS, not completely dead but almost. Try cleaning the CPS connector first, then try another CPS.
If the ballast resistor were at fault, it would stall as soon as you release the key from the crank position. Is this happening, or does it keep running for a few seconds with the key in the "run" position? If it dies when you release the key from "crank" , then its a bad ballast or ignition switch.
(Is there (good) fuel in the tank)?

for the few seconds it runs, does the throttle respond?

It does have throttle response for the few seconds, as well as it runs in the run position. As for the security system, how do I even know if it has one? I was told it does, but not sure where to look. I tried cycling through the door locks, but that didnt seem to work. The gas in it couldnt be that old, it was driven up until a few months ago. I really appreciate all of the responses I have gotten, please keep them coming.