1996 Ford F250 7.3


Had a hard time starting this morning, but started... as if the battery was dying.


Drove for about 20 minutes. Stopped the truck. An hour and a half later, it wouldn't start - it tried. Took the batteries to OReillys and had them charged and tested - needed to be charged. Put them in the truck and tried to start the truck. Still wouldn't start. Voltmeter on dash when I turn it to accessory says a little over 8 volts (barely above the acceptable mark) - but dips down really low when I try to start.
I took the batteries back to OReilly's... said it needed to be charged again. Batteries are only 6 months old.

 

Without question you need to have batteries in good condition for a 7.3 to start. It has to turnover at least a certain RPM and the glow plugs if working consume a good amount of power to get the engine started. If the oil is heavy because it's cold outside that places an addl load on the batteries. For what it is worth, battery manufacturer and cold cranking amps can make a world of difference. A check of the battery cables is called for to eliminate that possibility since they may be original and need to be confirmed in decent condition without internal corrosion.