1997 Explorer Won't Start

[dat1949]

V-6 4L SOHC----
I had very intermittent problem (on and off for over a year) where the engine would crank all day long but would not start. I would let it set for anywhere from 30 min. to over night, before it would start.
Finally I saw tip on this forum where someone suggested to check the crank rotation sensor connector for corroded contacts.
I unplugged and replugged the connector on last failure to start incident and then engine started fine. A few days later it failed again to start so I unplugged the connector and sprayed WD-40 in connector and worked it on and off a few times to clean the contacts. It’s been a couple of weeks now and no more problems.
Connector is located on front of engine, just behind lowest pulley(crank). Two wire plug with retainer clip. Don't loose clip.