Won't start when warm

Hey my mom has a 05 grand Cherokee Laredo. It's a v6 but I couldn't tell you what exactly it is. All I know is the engine will start as long as it's not up to temperature and run just fine. Once she turns it off she can't restart it until the temperature goes down. It cranks but won't start. Off the top of my head im thinking a sensor but don't want to tell her wrong. She can't afford to throw a lot of money at it. Ideas are appreciated.

Go to Advanced Auto or Auto Zone and get a free computer scan. Post the codes if any as this will guide to some problem areas. Does the engine turn over good when warm. Check for spark when warm.

No codes on the engine. It turns just fine. What would be the best way to check for spark? I don't have any fancy tools.

No codes on the engine. It turns just fine. What would be the best way to check for spark? I don't have any fancy tools.
Pull a plug wire and put a good plug in it hold the plug against a good ground have someone else crank the engine. Watch the plug for spark.
If you have spark you have a fuel problem.

Awesome thank you, I'll either have my step dad try soon or I'll see if I can get to it next weekend.

Whatever was wrong seemed to work itself out. The issue just went away on its own. Must have been a faulty sensor or something.