2001 Cherokee Limited
4x4 I6 4.0L
205k miles

Was perfectly fine yesterday, went to start it up this morning and just cranked and cranked and cranked (video 1). Tried starter fluid and nothing. Can hear the fuel pump start when set to run, and verified fuel in the fuel rail via the purge valve. Coil pack and plugs are less than a year old. Assumed it may be the crank position sensor granted the evidence I have. Got a crank position sensor and just installed it, but still won't start, although it sounds a bit different (video 2).

For context, it is currently -2° here, although, that's never been an issue before.

Any help greatly appreciated.

 

Upload the vidoes to youtube and share the link.

You need Air, Fuel and Spark, verify these before doing the parts cannon.
Also a helper to crank it for you.

Fuel: depress the scheader on the fuel rail to confirm pressure 🟢
Spark: visually confirm spark
Air: slightly depress the throttle when cranking

 

It's been a while since I've had an 97+, but I feel like that tachometer is supposed to move while cranking. All the other gauges do.
You have OBD2, so I'd start by seeing what info you can get from Torque Pro or OBDLink.
Where did you buy the new sensor? In my experience, a lot of aftermarket ones don't work out of the box.
I'd also make sure you have +5V and GND going to that sensor, pins 3 and 2.

Also, fuel pressure is important but does not prove you're getting fuel. Without the crank signal the injectors won't pulse, they're timed by the same computer as the spark.

 

In the first video, it sounded like it tried to start. Check your fuel pressure. You can also try spraying some starter fluid (or equivalent) in the intake to see if it starts up (albeit briefly). That will tell you if it's a fuel problem.

 

my 1996 or my 1998 jeep grand cherokee had this same issue. Ended up going the cannon route after the basics was checked.
My issues was any part put on and the jeep would crank and start just fine for one to two days.

started with the crankshaft position sensor
then the ignition coil pack
then plugs and wires
then distributor cap

and it was recommended to replace the cam sensor, which caused a whole debate online plus the auto stores did not have anything listed for cam sensor

I ended up replacing the cam sensor called ignition coil pickup sensor and never had a problem sense, this part is in the distributor right under the distributor cap.

not saying that's the issue but I'd start with that part as it would have saved me money, time, and aggravation

 

Fuel air spark...

Buy or rent a hydraulic pressure tester for fuel systems ( box store rental, harbor freight purchase ) to verify acceptable fuel pressure not just that the fuel rail gets some fuel.

Spark - pull spark plugs and inspect condition, dirty or even excessive fuel can mettle with firing. While you have 1 of them out check for spark. I would not advise grabbing a leftover random spark plug, pulling 1 plug wire and checking for spark that way because if your plugs are disgusting then you won't catch this issue. Again pull your plugs to check for spark

Air is simple enough - in wont explain this part

If your unsure how to troubleshoot ANY sensor specifically. Google or YouTube how to troubleshoot before you buy any of them. "This fixed my problem this one time" doesnt account for everyone's situation. Troubleshoot and find the fault - then replace when needed

 

I second the cam sensor. The cam and crank sensors work in tandem, crank sensor determines crank angle (obviously) and the cam sensor has two states to determine which stroke it's on, (compression or exhaust). They both need to work for the computer to time injector and coil pulses.

I've personally never had my cam sensor go out before the distributor but it is common.

Are you getting any obd2 codes?

 

Suck, bang, blow!
I'd start by verifying my gas didn't have water, contaminants in it. (Put heat in tank)
I'd verify my battery was good and starter was receiving proper signal.
I'd verify my grounding points were clean, solid and absolutely capable of doing there job.
I'd pull spark plugs and rail to inspect each plug.
I'd verify each fuse was properly functioning or able to complete circuit.
I'd test fule pump circuit and any appropriate relay/fuse.
I'd verify my mega fuses were good.
Pull air box cover and visually inspect filter and duct intake.
Clean throttle body.

Then and only then would I move onto parts cannon. Test and retest. And yes it has been brutally cold. I'm north of you in wi. And had a battery die in (-19 air temp, -30 wind chill). It was brutal trying to work. I damn near got frost bite.