I have a 92 jeep Cherokee..I'm having the same problem..Just got the rear main seal changed and it ran fine for two days..Took my son to school ran fine, went to take my daughter to school and nothing..Doesn't turn over, Put a brand new battery in it and it has power just wont start.I looked and I think someone at some time took the clutch sensor out cuz there is only a hole where it was..My brother owned it and said you did not need to push the clutch to start it ever since he's had it..If yours is automatic maybe it's the Neutral safety switch, or if its manual the clutch switch...Other then that I'm still searching....Yea they do have a starter relay Under hood, passenger side, upper engine area, front of blower motor, mounted on wheel well Im gonna check that next...Let me know if you figure anything out....