1993 Ford F-150 2 wheel drive straight six

Check engine compression, fuel pressure and ignition spark

I would ignore the battery being low, if it cranks but don't start. You need to check the basics of spark, and fuel. One quick way to determine if fuel is absent, is to spray some starter fluid in the throttle bore. If it fires and runs a few seconds, then dies, you have verified that you have spark, but no fuel, either pressure or injector fire. If I am not mistaken, your vehicle also has an inertia switch that will disable the fuel pump. If there is a possibility that the vehicle was bumped into, it may have tripped. If you have an owners manual, it may highlight the location of this switch. These switches can fail as well. If you determine there is no fuel pressure, you need to consider this switch before just assuming it is a fuel pump.