Wrangler starts, runs for 3 seconds?

Question

I've got a 2000 4-cylinder manual Wrangler. The other day, after stopping for a bit in the back-country of Big Bend National Park, we started experiencing a problem. The Jeep would start and run normally for roughly 3 seconds, then quit as if the ignition were turned off. I checked everything I could at the time, including fuses, relays, fuel delivery, and airflow. Fuel was near full and oil pressure read normal before the engine cut off. Problem is reliably repeatable (meaning I still can't get the blasted thing to run for more than 3 seconds). Couldn't find anything obviously wrong, which makes me suspect it's an "electronic" problem. Does anybody have any ideas what to look for?

After waiting for about 8 hours, the Border Patrol finally found us and dispatched a *very* expensive tow truck to haul us back to our RV. With the Jeep malfunctioning, we cut our little vacation short, hooked it up to the RV and drove home. I'm reluctant to take the Jeep off-road again until (1) I know what caused the problem and (2) have a way to fix it (at least temporarily) in the field should it happen again.

Thanks for your help, Bill

snipped-for-privacy@yahoo.com

Jerry Bransford · Accepted Answer

Do you have a security "Sentry" key system? If so, I'm betting it's related to that.ElAlumbrado wrote:

James · Answer

Were you using an after-market key, just recut from the original?

I had a key made at Home Depot, not realizing that it needed to the the electronic (encoded) key. It would crank, run 3 seconds, and shut off.

As Jerry noted, it may be security related.

--james--

SteveBrady · Answer

It shouldn't start at all if you have the wrong key.At work we have a cherokee and it's key fits in my ignition...and will turn it, but the KEY-shaped light comes on, on my console....no start though1

Jerry Bransford · Answer

Nope, it will start even with the wrong key and then after the code is checked, the engine will be killed if the code doesn't match. I discovered this when I had an extra key made for my wife's JGC that did not have any kind of security chip.

Jerry

SteveBrady wrote:

ElAlumbrado · Answer

Key is the same key I've been using for 5 years. Perhaps a sensor failure of some kind?Bill

ISellJeeps · Answer

try the crank position sensor

Eric · Answer

A friend of mine had a cougar that did the exact same thing. It was actually the ignition switch itself. The tumbler that the key inserts into. As it sprung back from "start" to "run" it would cut off. After starting it, I'd let go just enough to disengage the starter. It would run forever, until you let the key go.

Eric

Will Honea · Answer

I would be checking the fuel pump.  One that's on it's way out will dothat: enough pressure builds up to start but not enough capacity to even keep up with idle RPM fuel usage.  A badly clogged fuel filter can act the same way, but you should have had some warning if that wasthe case (stumbling at higher RPM, etc.).

L.W.( Ãill ) Hughes III · Answer

Could be, if the Auto Shutdown relay doesn't get a signal from theCrank Position Sensor it will shut down at three seconds, as per:         God Bless America, ßill O|||||||Omailto:     ISellJeeps wrote:

L.W.( Ãill ) Hughes III · Answer

Hi Bill,    Pull the codes:          God Bless America, ßill O|||||||Omailto:      wrote:

Jerry Bransford · Answer

It won't even start without a good CPS signal which is the engine's Master timing signal that provides timing for everything.  Without the CPS, it has no idea even when to send spark to the spark plugs.  Yes the PDC shuts the ASD relay down in 3 seconds if any of lots of signals are not there but the engine won't even start without a good CPS timing signal.L.W.(ßill) Hughes III wrote:

Wrangler starts, runs for 3 seconds?

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