Details - Stock 95 ford f150 which has been used hard and put away wet.

Last night, it would not start.. no click no fuel pump whine, nothing. Turned on the headlights and the battery was fine. It starts, turn off lights and it still starts. Let it sit for an hour and it won't start until you turn the lights on. Then it is fine until it sits again.. My son and I are stumped on this one.