2002 Jeep Grand Cherokee, cranks over, but doesn't start.

Sounds like either a failing ignition control module or a dying fuel pump. Sometimes the ignition control module (ICM) will work fine until it gets hot. Then it'll break down and quit preventing the engine from starting. If you suspect the fuel pump, hit the bottom center of the gas tank a few times with a hammer when it won't start. If that gets you going it's definitely the fuel pump. Hope that helps! Jim

My GC did the same thing, they have problems with crank and cam sensors. I replaced both and problem went away. Note use genuine Jeep parts as they don’t like aftermarket sensors, I found that out the hard way.

When an engine is run for a while and shut off, then won't restart for a while, it's frequently due to leaking injectors. That cloud of fuel mist in the intake gets sucked in and floods the engine. When leak is severe, this can cause a running engine to just stop while in traffic..... Next time this happens, put the gas peddle to the floor. This is a programed Wide Open Throttle that is designed to clear out the excess fuel and get you going again. Have your injectors checked; they likely need to be replaced, and in a ten year old Jeep, that's pretty common.