When the main fuel relay acts up the car cranks but doesnt start. It basically stops the fuel pump from running. There are contacts in the relay that actually crack over time from the constant heating and cooling of them. When the car gets hot either from a trip or from sitting in the hot sun they tend to lose contact. Then once they cool down they reconnect.
The relay on your car is located uo under the dash on the drivers side.
CLICK HERE for the location.