I bought a Jeep at auction for a friend who is down on his luck. The jeep is a 99 with the 4.7l its a limited with quadra trac awd. It only has 120k on it and ran perfect when I gave it to him. Now as luck would have it he started having problems shortly after I gave it to him. The problem he is having is it will randomly die for no given reason. Does it while driving or while idle. No sputter or anything else just dies cold. When it dies all the gauges drop to zero. The check engine, oil lights etc. kick on but the dials read nothing. We hooked it up to a code reader and its not pulling any codes. We checked all the fuses and nothing. The wires seem good but only looking for anything obvious. We replaced the crank sensor but no luck. We are thinking maybe the cam sensor but just don't wanna throw parts at it. Any advice or suggestions? His wife is about 7 months pregnant and they already have two little ones. They are dependent on this jeep and in a real bind.

Did you check the gas flow? There maybe a plugged up fuel filter or bad fuel pump/s.

Fuel filter probably in tank..
when it shuts off, spray some starter fluid in throttle body and see if it runs on starter fluid and then dies..
If it does, the fuel pump is cutting out..
If it does not start with starting fluid,  should be electrical..

Sounds like bad wiring or a computer/PCM problem.

I would think ignition switch, if the temp gauge is reading zero the power is being cut to it.

Crank or cam sensor is the most likely culprit here.  Since you already did the crank, it's probably the cam.  If those go erratic in their readings to the computer, the engine just stops.

Jeepforum or wjjeeps.com is gonna be your best resouce

Trying to diagnose w/o codes can get expensive quickly.





Crank (which you replaced) and cam sensors would have been the two I'd suggest.  





It seems to be acting as though the key was quickly turned to the off position and back to the run position.  Could start there inside the steering column.





I remember a customer with a VW that would cut out whenever they went over a big bump.  Turns out their 1 pound keyring with all kinds of crap hanging off of it would actually turn the cylinder just enough to shut the car off.  





These kind of problems can be maddening to solve.  Good luck.

 

Pretty certain its not a fuel issue. Like I said the gauges including the volt gauge drop to zero even though the the engine turns over just fine. You can keep trying and the second the voltage gauge goes up the jeep fires right away like nothing ever happened. I'm certain its electrical. Thought it was a crank sensor but that didn't do it now I'm leaning towards a cam sensor.

This is probably a good place to start.

I thought the same thing, but my '95 jeep did the same thing and it turned out to be the fuel pump module anyway, crapping out at around 190k miles, which is normal apparently.
YMMV, just my experience.

If it has a distributor, it is either an ignition module or ignition related. Otherwise, it is a crank or camshaft sensor.

Hook up a fuel pressure gauge and see what it reads. If this is too complex, pull the fuel filter off, crank the motor and see if gas pisses out.

But it isn't a fuel problem.


This is a basic ignition problem. Ignition module-crank or cam sensor.

Does it have "Loctronics" on it? My 99 did that shit all the time and the dealer finally changed the "Loctronic" plug and it never did it again..

Mine was doing this.



I had a bit of corrosion inside the battery terminals.   They looked great,but there was white powder between the contact surfaces.  



A bit of sandpaper and steel wool made the problem permanently disappear.  Was damn near free to boot.

Sputtering death or sudden death? Sounds like sudden which would lead me to think spark or ignition switch problems. Ignition seems more likely if no codes are being thrown.

No codes but when its dead I crawled under to listen for the fuel pump to kick on but heard nothing. Would a cam sensor pull a code? If a cam sensor goes out wouldn't it kill the pcm cutting everything off including the gauges, fuel pump etc? I've replaced fuel filters and pumps. But if it where either of these the dash cluster would still work fine. As for battery connection we already pulled them and cleaned them.

Not even sure what loctronic is... Will have to google it.

Ok the jeep does have loctronic but even using a walmart key will not duplicate the problem. Without a chipped key it starts and then dies shortly after. I can hold the original key up to the egnition and start it with a walmart key then remove the chipped key and it will run/drive fine. The it chipped key is needed to start but once running the chipped key is no longer needed to keep it running.