F150 cranks but won't start

Vehicle: 2000 Ford F150 4x4 - 5.4L engine with approximately 122,000 miles. I have never had any major problems with this vehicle and it has been serviced regularly.

A few days ago (on 8-20-2008), after a 2 hour drive during a hot afternoon, I stopped at my Father house for a visit. Just prior to stopping (i.e., shutting the engine off), I noticed that the temperature gauge was indicating a reading at its extreme cold position and the engine was idling too fast 1100-1200 (instead of its usual 700-800 rpm idle speed). (Normally the normal temp gauge reading is in the center of the gauge - half way between cold and hot.) I shut the engine off and about 30 minutes later checked the oil and coolant levels which were good and I didn?t see any leaks or anything else abnormal. I assumed the abnormal idle speed and low temp gauge reading were some sort of freak occurrence. About 1 hour after shutting the engine off, I attempted to start the vehicle to move it, but while cranking motor turns normally the vehicle refuses to start. I have never had a problem starting the vehicle. I have checked all the fuses and the fuel pump seems to be clicking on. No scan codes are present. Any suggestions will be greatly appreciated.

I would first make sure spark is getting to the plugs. If that is good then spray some starter fluid into the intake and see if the engine responds to that. If so then check the fuel system for a problem.

Check the temperature sensor on the engine. Make sure the wire to the sensor is connected well. If that is good then I would check the resistance of the sensor when the engine is cold and hot and see if the resistance is changing with the coolant temperature. If it isn’t then the sensor is bad. Also by grounding the sensor lead the gauge may show hot.