98 XJ Problems: starts..but wont stay running..

I just got an 1989 jeep cheeroke, for FREE everythings works awesome..just doesnt run and is rusty but this is gonna be a trail rig only... i can do just about everyhting suspension wise, but iim definaly not an engine guy.

The XJ starts every time no problems BUT idles alll the way up to about 2000-2500 runs for like 1.5 seconds and then just idles back down to ZERO and shuts off . if you give it gas it'll rev maybe one time then putter out.. the enitre full assembley has been replaces. line,filter,pump,screens and regulator, and i belive the injectors.
we got into it a little today and its getting plenty of fuel.. it just seems that once it starts and then comes back down to idle, the XJ just wants to shut itself off. and like i said its getting fuels because if you pump it while its trying to dye you can smell the raw fuel. and some even comes out of the exahust, even disconncted in case it was gfetting TO MUCH fuel but that definatly wasnt the problem either..For some reason we really think its electrical...somwhere... because the engine doesnt burp or sputter out... it just idles up and then back down to off..

electrical somewhere..?? im no master mechanic but im not exactly where to start now.

please someone give me ideas where to start out at.. i know i got this for free and using this as my cheap truck challenge. I REALLY dont want to take it to a mechanic.

thanks scott

ok first this is a renix engine management system.

it sounds like u are having problems with your TPS(throttle position sensor)
there are many sensors u can actually test. If u search more in this forum u will find alot of info on testing these sensors. If i find the posts, i will link to them.

but here is a link for "Renix" it tells u how to check sensors.

http://www.pirate4x4.com/tech/billavista/PDFs/Jeep_Renix_Fuel_Injection_manual.pdf

Thanks alot

and sorry for the topic, it says 98 XJ but as you knew its an 89 my mistake..

but for anyone else, it is an 1989

Hmm.

After it starts the stops check your fuel pressure. The ECU only runs the fuel pump for 2-3 seconds before shutting it down untill it sense the engine is running, then restarts it. It kind of sounds like your pump is not coming back on perhaps.

Also locate the ballast resistor on the right fender and bypass it...does that fix it?

Ah, 89 not 98? Definitely check that ballast resistor. The resistor is meant to make the pump run quieter, but it will run fine without it.

Where is that Ballast Resistor Located? In the right or left fender? some threads say it's le driver's side and here you're saying it's on the passenger side. Where is it exactly?

Ballast; for sure
Its there, just look for it it has wires and its whiteish and ceramic, and probably green from corrosion

WOOOOOOOHOOO YOU GUYS ARE GREAT... it was the ballaist resistor! GET THIS... i go out to check it.. its plugged in so im like on, one guy said to unplug it...same problem... so i go to plug them back in and im liek well lets see if i reverse the wires... and PRESTO it fires right up and has been running for about 15 mins now! THANKS!! NOw its time to start hunting around here for a lift ,tires and lockers!!

Thanks a million guys!!
scott