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Not starting when its Hot outside could be a few small cheap things.
1. Is a dirty Air filter. 2. Is a Dirty Fuel Filter3. Is a defective gas cap.It could also be dirty fuel injectors or worn spark plugs.
I would recommend a tune up. He might also want to have it checked for Trouble Codes. Any Auto Parts Store will scan his Jeep and inform him of any stored Codes. If any are present you can give them to me and I can give further instruction on how to correct it. :)Its a whole lot cheaper to fix a car then it is to replace it :)Please reply here with any additional questions you may have. I am always here to help. My goal is to provide you with Excellent Service. If you feel I have answered your question and are happy please Rate. If not, just let me know what I can do to help. :)