2001 Jeep Cherokee doesnt run, what to check?

[V]

It's a sport model I think. 4.0L I6 engine, automatic.
Starter is good, battery is good, cranks over fine but doesn't fire.
Checked the valve on the fuel rail and seems to have pressure, and builds up pressure again when turning the key off and back on.

I see that the coil packs are a one piece unit so not sure how to check for spark.
I tried unplugging the crank position sensor and plugging it back in, but no change.

Any known common issues to look at?

[sweetbmxrider]

Cps is common. You can unbolt the 4 bolts on the coil pack and check for spark at any of the boots however you can. They are common failures too.

[ThoR294]

well if you have fuel pressure and its cranking... check for spark like bmx said. if you have spark then you probably have a crank signal. if you DON'T have spark, see if the injectors are firing (you'd probably smell fuel by now if it was firing the injectors). if they are not firing, then I'd look at the crank (assuming jeeps fire based upon CPS... like bmx said)

[V]

well if I don't have spark, how do I know if its coil pack or cps? I read a few places that a bad cps can still test good using the ohm reading.

The coil pack or cps could be bad but without replacing one I cant know about the other.

the coil pack is 83 bucks on rockauto and the cps is 41. I may just tell my friend to get both and cross his fingers, lol.
I hate just throwing parts at something, but without ruling one, or both, out I dunno what else to try.

[Tru2Chevy]

I don't play with the coil pack 4.0s much, but I think there is an easy way to test for a signal going to the coil rail.

- Justin

[ThoR294]

If you don't have spark... Check for fuel. Pressure doesn't guarantee the injectors are firing. You can get a scanner and maybe check for codes or see If the CPs is sending an rpm signal

[sweetbmxrider]

Originally Posted by V

well if I don't have spark, how do I know if its coil pack or cps? I read a few places that a bad cps can still test good using the ohm reading.

The coil pack or cps could be bad but without replacing one I cant know about the other.

the coil pack is 83 bucks on rockauto and the cps is 41. I may just tell my friend to get both and cross his fingers, lol.
I hate just throwing parts at something, but without ruling one, or both, out I dunno what else to try.

If you have a scanner with data stream, check for rpm while cranking. That will tell you if the cps is working or not.

IGNITION COIL RESISTANCE - 4.0L ENGINE
PRIMARY RESISTANCE 21-27°C (70-80°F)
0.71 - 0.88 Ohms

COIL RAIL - BLACK 4 WAY CAV CIRCUIT FUNCTION
1 K19 18GY IGNITION COIL NO. 1 DRIVER
2 A142 18DG/OR FUSED AUTOMATIC SHUT DOWN RELAY OUTPUT
3 K17 18DB/TN IGNITION COIL NO. 2 DRIVER
4 K18 18RD/YL IGNITION COIL NO. 3 DRIVER

[B4C]

4.0's are known for killing crank position sensors, I have seen cam positions sensors go bad as well but not as common, I would bet its the Crank sensor.