From what you've said so far, it sounds like a fuel pump problem. Most likely a weak pump getting ready to fail. It sounds like the fuel system is losing prime when the jeep sits. When the key is turned on the fuel pump is energized for a couple of seconds building pressure back up allowing the jeep to start, but if you try to start it right off there isn't enough pressure. I would try to get my hands on a fuel pressure gauge to verify this, parts stores usually have them to rent out most of the time for free with a deposit. Also try to isolate the source of the clicking, it's most likely the fuel pump in the tank but sounds like it's coming from the dash while sitting on the jeep. If the clicking isn't coming from the pump, it may be the fuel pump relay which may be another problem all together with the electrical system, although I'd bet on the pump.