Have the intake air temp. sensor checked .Two wired plug on top of intake manifold. Check fuel pump pressure.
A 2002 Jeep Grand Cherokee engine that cranks but is not starting and has no dash gauges is experiencing an electrical system failure. This can be a result of a faulty ignition switch or damaged wiring.
If the engine cranks & cranks & cranks before it starts even though it's warmed up already.
No of cranks used in 6 cylinder engine
the engine will turn over a few times before starting, if it starts, and it will feel sluggish
What to do before starting auxiliary engine?
Replace the engine coolant temp sensor.
The early 4.7 engine in the grand cherokee,dakotas,and rams have had problems with cylinders on the rear left of the engine,starting with a knocking then overheating and seizing .
I'm no expert, but my friend had a similar situation in a carburated Toyota due to a clogged fuel filter. Fuel filters need to be changed every 30,000 miles or so. It's a cheap and easy fix - try that first.
Diagnosis: Engine Won't Start or RunCheck related link below
Sounds like your battery may be very low; if it turns over slowly when it eventually starts turning, definitely try jump starting or charging the battery and trying again.
on the 4.0 jeep, if it cranks, but wont start, try replacing the crank sensor, located at the top rear of the engine, at the transmission
Check engine compression Check engine timing