[ford38v8]

You’re not getting enough voltage to the coil while cranking. For this, check resistance drop at each connection from battery to coil. The only significant voltage drop should be the resistor under the dash. Check condition of battery cables and starter cable, and also in those cables, confirm that you have 6 v cables not 12v cables, and importantly, the connections themselves. Check battery before you attempt starting, should be 6.4 or above. If all of the above checks out, give your engine a chance to start after releasing the starter button before turning off ignition, as at that point you have full ignition voltage without the starter drag on voltage. If all else fails, while cranking, and only while cranking, bypass the resistor under the dash.