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xj starts, but dies immediatly

J

jeep1947

NAXJA Forum User
Location
Michigan
I have searched and tried alot of things already and nothing has worked yet. The engine cranks over normaly and starts normaly, however it dies after <5 seconds. when it starts it sounds normal and the rpms are normal for starting/ idle. I thought it was fuel related but i released alot of pressure out of the valve right after it died. I tried unpluging the map and that did nothing. I am thinking it could be the IAC, but that is just another guess. would the iac make it do this? and if it is the iac can i just clean it or is my best bet to get a new one. I would just try cleaning it however i am at school w/o ANY tools and will have to buy more to even check this.

1993 4.0L cherokee
 
It should still run if the IAC was bad or gummed up. Sounds like a fuel problem to me. I'd check your fuel filter to see whats in there- water, dirt. Your getting air and it seems your getting spark.
 
when my 87, 4.0 did that, it was because i knocked one of the wires off of the resistor mounted on the inner fender. not sure if your year has the same thing. resistor is in the fuel circuit.
 
no its not a fuel problem, because if i play with the peddle i can keep it idleing at 3,000 rpm. and if the map sensor were unpluged the computer would use a default input. Still have not figued anything out though.
 
try wiggling the wire that goes to the CPS (crank position sensor).
my jeep was dying out on me at redlights, i played with that wire a bit, and it's been doing me good since. OR replace the CPS
 
This will happen if the battery is on the way out, the IAC doesn't reset itself properly and it wont idle. Does it run if you keep the rpm up for a few minutes and then take your foot off the accelerator? If it does then I'd say it's the battery for sure.

Cheers
Steve
 
A car with a good alternator will run without a battery.
 
jeep1947 said:
no its not a fuel problem, because if i play with the peddle i can keep it idleing at 3,000 rpm. and if the map sensor were unpluged the computer would use a default input. Still have not figued anything out though.
Click to expand...
I learned something then.
 
Dont think its the cps. The cps gives the computer the syncronization pulses in order to fire the injectors and spark plugs at the correct time. If cps pulses are missing they should miss at any rpm.

Torfinn
89 xj 4.0 limited
 
I was just about to say that... that TPS is a common problem on XJ's. It will get stuck sometimes and have you idle high until it gets unstuck and sometimes it'll come out of calibration enough to cause you to die on startup...

Do a search for TPS calibration or, if it's really old, just buy a new one (but it still has to be calibrated...)
 
my tps went out about 3 months ago and would not let my trans shift, so it was replaced. I do not think it would go bad that quick, but it does sound like that could be the problem. How would i go about calibrating the tps, because i donot think i adjusted it when i got the new one. Also another piece of info i have been thinking about was for the past couple of weeks before it broke it would have an occasional stumble or misfire i do not know if this will help narrow the possibilities or not. but just to clarify its probably not the IAC? that seems to be the general response.
 
jeep1947 said:
I have searched and tried alot of things already and nothing has worked yet. The engine cranks over normaly and starts normaly, however it dies after <5 seconds. when it starts it sounds normal and the rpms are normal for starting/ idle.
Click to expand...
I have an '89 XJ with a very similar problem that I've been trying to fix over several months now.

In my case, the engine shuts of within 1-2 seconds of starting. Here is my checklist:
1) Check resistance across the terminals of fuel pump ballast resistor on drivers' side inner fender. If circuit open, replace or better yet, cut the connectors out and join wires together.
2) Pull __vacuum line__ off the MAP sensor. Leave the electrical connector plugged in. This is the only way my Jeep will run now. With this hack, the MAP sensor will tell the ECU to make the fuel/air mixture richer that it should be. My current theory is this is related to fuel injectors going bad and not spraying per specifications, which leads to engine shutting down.

This is the thread where a lot of knowledgeable people helped me with diagnostics: http://www.naxja.org/forum/showthread.php?t=71001&highlight=XJ+start
 
Last edited:
A brand new ballast resistor is only $7 CAD, that's like $4-$5 US, from the dealer. I wouldn't join the wires together just for that simple reason. I'd say that's what your problem is cause I just fixed the same problem a couple of days ago.
 
Try unplugging the vac line to the egr valve, mine did the same thing and if I plug in the EGR it drops to around 100rpm and then dies. Replace your egr valve or clean it out if that does anything.
 
jeep1947 said:
no its not a fuel problem, because if i play with the peddle i can keep it idleing at 3,000 rpm.
Click to expand...


HEAR ME OUT PLEASE. About 3 months ago i was sitting in the drivers seat of my undriveable 1988 xj saying almost word for word what you said above, because i had the same problem as you. I could start it, idle for ~3-5 seconds then die. Start it again, give it gas bring engine to 3,000 rpm, and it would run all day. Turned out to be the FUEL PUMP. The rubber hose going from the pump to the fuel line ruptured and was spongy. When you gave it gas, the pump would ''manage'' to get enough gas to keep it running. Changed the tired old 17 year old pump and two inch rubber hoses and the fuel filters and it has 35 psi as runs good as new. And by the way, everything everyone else said, i tried myself before i changed my pump.


--Long story short, dont rule out fuel issues. Good Luck.
 
Thanks for all the help it turned out to be the resistor on the drivers side fender. I looked at it and saw a crack in it, i then pulled on it a bit and it easily became two pieces. It turns out it had been coroding awhile and had finnaly lost all connection cost me about $5 to fix. Thanks again.
 
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