2000 XJ Starts and Shuts Down. Please Help!

I know this is posted everywhere on the forum, but i am getting pretty confused on what to do. So I am very sorry for the repeat. Just need some help please.

Its a 2000 xj 4-door sport. 4.0 high output engine. The problem just started yesterday.

It starts like a champ everytime, runs for 2 seconds and shuts down. If i turn the key all the way to the off position it will start right back up again then shut down. If i leave the key on the on position and try to start it, it will just sit there and crank over.

People have said it could be the ballast resistor. But i dont think the 2000 have them. "please confirm"

Also people have said its the relays? Not that smart with engine work, more of a lift and body work kinda guy.

So if you could put it in simple terms, names, and places in the engine compartment i would love you guys forever. She is my baby and i need her back. Thanks

You are correct in the "no ballast resistor" idea. you need to figure out if you are missing spark, fuel or both. I think that I would put a fuel pressure gage on the rail.

Ok i will go out and check the spark right now, and let you know whats going on.

I know the crank position sensor can go bad. Or the cam position sensor too maybe? These are the things I saw when trying to make a 2000 run/ run smooth.

Can you keep it running with some throttle?

It almost sounds like its the VATS system giving you problems. What color are the heads on the ignition keys? They should either be grey or black. Grey are the security keys and the Black are just regular ones.

It could also be that the ASD or Fuel Pump relay is not getting a signal that the engine is running after the ECM gives it the initial pulse to prime the pump. When you first turn the key on you should hear the pump run for a few seconds to build pressure and then stop. Once you start cranking the engine the ECM should re-energize the relay making the pump run.
You can check this a few ways. Either hook up a fuel pressure tester and see what the readings do once you start cranking the engine. If it drops off rapidly to zero the pump is not running. The other is to take a test light to the power feed that runs the pump and see what you get. It should show 12v for a few seconds when the pump primes and then go out. It should then come back on during cranking and stay on with the engine running.

Some older cars used a resistor to step down the voltage to the ignition coil from 12v to 6v to help the coil last longer. They would use the 12v during startup to make a hotter spark and once the engine started it stepped down. I've never seen or heard of this on a 2000.

No i can not keep it running with some throttle...the rpm will go out....then die back down.

And its a grey key. Is there a sercurity switch that needs to be pushed at all. I am going to go and test all these right now and i will post a reply. Thank you very much for the info.

What does the key light on the dash do when this is happening? Do you have a second key to try? This does sound like its the Sentry key system acting up.

Ok i tried my other key...but it is grey as well. When i turn the key to ignition before i start it, on the dash...the circle with the key and line through it blinks on and off. It is not steady. And does the same thing when i start it up.

From the looks of it, its a sentry key problem. It says if the light is flashing then it is not recognizing the code of the key. I tried both keys and still the same thing is happening. What would be the next step?

Should i unhook the battery for about 5 minutes and hook it back up?

You could try unhooking the battery cables and touching them together. Don't need the 5 minutes part.

This might help-> http://www.xjjeeps.com/com_xjjeeps/tech_reference.asp?section=2&ID=1

I had pretty much the exact same symptoms in my old '88. Would start up and run for a second or two, then die. Turned out to be a bad fuel pump relay. I swapped it with the relay for the AC (since it didn't work anyway) and it fired right up. Relays should be in a black box just inside the fender on the passenger side.

i know its a different animal but we had the same problem at the shop with a 2000's grand we thought it was security and chased that rabbit for a while then changed out the ecu and the problem went away. there is a company that sells "new" ecus for cherokees on ebay for about 150. best of luck, let us know what it turned out to be.
jake

20jeep00xj said:

.the circle with the key and line through it blinks on and off. It is not steady. And does the same thing when i start it up.

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That is telling you that it doesn't see a correct key. Disconnect the battery and see if it helps. I doubt it will. You can check to see if everything is hooked up correctly, primarily the ring around the ignition under the trim on the steering column. Other that that I don't know of a way to diagnose it with out a DRB III, which most likely means it will have to go to the dealer. Its actually a pretty worthless system

Switched out relays and still nothing. I am sure i will have to take it in. And yes i agree its a worthless system. I am trying the battery today just crossing my fingers in hopes that it works. Thanks for everything.

"If the world was run the way this forum is....it would be a far better place!!" Thanks everyone

did you change spark plugs latley and remove the coil packs? If you did loosen the bolts on the coil pack a little and adjust the coil pack so it lines up right. if you didnt move coil pack at all before just try it anyways,you may need a new coil pack it could be weak. good luck

With the key light blinking it isn't the coil packs.

With the key coded security system I am under the impression the vehicle's engine would not even crank. His symptom is starts and dies. This sound more the ECM is either not sending a signal to the fuel pump circuit, or the circuit has a failed component or does not recognize that the vehicle is running

No, the engine will crank, run for a second or two then cut off. The system is not recognizing the key as indicated by the flashing no key light.