'85 Cherokee Starts, then stalls...sometimes

[Packrat]

I have an ‘85 Cherokee with the 4 cylinder engine. It is fuel injected. I am the second owner of it, it was three years old when I bought it. I ran it totally trouble free for 120 K when the body rusted out. Three years ago I took it off road and retired it. Since I have a very long driveway and a wood lot I put chains on it, mounted a plow and only run it when I am cutting wood or plowing snow. This summer I went out to start it and it started right up like it always has, only this time it ran for 5 or 6 seconds and sputtered and died, as if it ran out of fuel. Several more attempts to start it and it does the same thing each time. It always fires right up an runs for 4 or 5 seconds after I let go of the key (so it is not the ballast resistor).
If I can time it right and floor it just when it catches it will rev up and it seems that if I can get it over a certain RPM then seems to run OK. After running for a while (maybe 10 min, maybe an hour, maybe tomorrow) it will sputter and die again. When I try to start it might start up or it may start then sputter and die. I may or may not be able to keep it running there does not seem to be any rhyme nor reason if it will run today or not.
I left it in the woods for three days the last time it happened and when I went back in with my tractor to pull it out It started and ran fine so I drove it out. I ran it for a week on and off with no problems, I was coming out a few days later and it died and would not start until next day. Guess it was tired of workin'.

The CPS was replaced last winter and tests ok,I got a general tune up last year when I put in the CPS. I have put Dry-gas in it and changed the fuel filter and it did not help. When I changed the filter there was no evidence of water in the fuel. There seems to be adequate fuel pressure at the fuel rail, even while it is sputtering and dying. It seems like the injectors are being told not to inject.

Anyone ever run into this before? -Thanks, Packrat.

 

[MudderChuck]

Not real familiar with the four banger. But I have an old Suckzuki, that I raley run. Fuel turns to chit after a while, I´d try fresh fuel and and some injector cleaner first. Sounds a lot like a CPS, typical symptoms when they act up. One quick test is when you have a no start is to unplug and plug up the CPS again, if it starts up you´ve probably found the problem. Stalling is often a fualty EGR valve, pull it off and make a plug for it. There are two types, not knowing which you have, I´ll say if you plug it look close, you sometimes have to put a screw in the exhaust part of the valve seat, in one type in the other you just need a sheet metal cover and some sealer.

 

[jeepmaster]

i had the exact same thing happen with my 96' i took it to 3 different shops and they replaced just about every sensor on the jeep, nothing helped. they could always get it to run, but as soon as i'd take it home, it would stop working. the only thing i could figure out was maybe the spare key i gave the shops was the fix. i swapped out the spare key that i gave the shops with the key on my key ring and the jeep has run perfectly ever since. i have no idea how this works, but im not complaining. maybe its worth a try for you? just switch up the keys

 

[XJNick]

Jeepmaster, Your Key switching solved your problem due to the onboard immobilizer system installed on most modern vehicles. The immobilizer system receives a signal from a small microchip imbedded in the key. If the signal form the key maches with the ID code in the Jeep's Powertrain Control Module (PCM), it will allow the Jeep to be started. If the signal from the Key does not match, the Jeep is immobilized.

This system did not exsist back in 1985 !!! :mrgreen:. Therefore anything relating to a keyed immobilizer system would have no effect on any Jeep made prior to OBD-II diagnostic systems (pre 1995).

The only way a key could possibly affect a 1980's Jeep would be if the key is worn down so much, it doesn't engauge the ignition switch (this would be a very obvious problem) :mrgreen:

-Nick :!:

 

[Packrat]

We had a snow storm this weekend and I plowed with it. It plowd fine for a while and did stall twice, both times it took 20 minutes to start and run, (more than about 5 seconds). One time I frigged with it for 20 minutes and then it started and ran, the next time I took a break and let it set for 20 minutes and then it started and let me finish plowing.

While I was playing with it trying to get it started the first time it quit I unplugged all 4 of the sensors on the intake manifold and it did not make any changes.

Just for kicks after it started I unplugged the same 4 sensors and it still continued to run, although it was loading up a bit and running rough, about what I would expect I have not tried the EGR valve yet, I'll look it up in my Haynes manual and give it a try.

You are correct in the symptom resembling a CPS issue, If it were not less than a year old I'd jump on it and replace it.

 

[XJNick]

I'd be careful when playing with the EGR system. Your engine won't last long if you disable any part of the EGR system :mrgreen:

-Nick :!:

 

[Packrat]

Thanks for the tip on the EGR, I'll not run it without one any longer than it takes to test it.
-Packrat

 

[olsendave]

I am newer at this then the others, but I have to ask, Do you have the key problem with that old of a Jeep. I have an 89. (Just saw the other guy said the same thing) Had the same problem. Replaced the starter sensor coil, something like that, before I knew anything, about 4 times. It turned out it was a faulty wire right on top of the engine. My Jeep would start, quit. Not start at all, then start the next day. It turned over fine, but wouldn't start. Sometimes it just ground itself painfully.
I would suggest checking all the wires. It can't hurt.


Dave
89 Jeep Cherokee
Learning the Ropes.

 

[XJNick]

I am newer at this then the others, but I have to ask, Do you have the key problem with that old of a Jeep. I have an 89. (Just saw the other guy said the same thing) Had the same problem.

Not sure is you're asking a question? No, In general the "bad" key theory mentioned above is ONLY applicable to newer primarily OBD-II compatible Jeeps (1995- up). Jeeps made prior to like the mid 90's don't have micro chip keys.

-Nick :!:

 

[Jason01]

I would allmost have to guess that it is something with the ballast resistor. I would carry a small piece of wire with me if I was you, and when it dies again, wire it across the ballast resistor and see if it runs!

The reason I am saying this is that when I was doing a compression test on mine, i pulled the wire on the ballast resistor(so as not to load up the cyl. on fuel), and when I went to start it agian, it would start, die, start, die, start, die. If you held it to the floor, it would run for a few seconds. Then I realized that I unhooked it. I would try it. Cant hurt much to try it, can it?

 

[Packrat]

OK, good possibility, However if the ballast resistor is faulty holding the key in the start position will keep the engine running, (real rough on the starter though, kids do not try this at home!) The engine typically would die the moment you released the key from the start to the run position, but I'll mak up a jumber and carry it in the rig.

I have installed an ignition spark detector inline between the coil and the distributor. A pair of extra long plug wires has alowed me to install it outside of the engine compartment duct taped to the top of the hood where I can see the ignition spark while the engine is running. I know sort of a cobbled up RUBE GOLDBERG affair but we have another 2 foot snow storm coming today and I will be out plowing by sundown. The moment it dies I will know if the ignition is shutting down or if it is on the fuel side. I think it is in the fuel system because it acts like it is running out of gas. I havn't had had a chance to look up the EGR Valve yet. Thanks for the tips. --Packrat