I have power but my 1990 ford ranger clicks loudly and wont turn

well this is your first request with fixya ----battery has a charge is it turning over and not starting --or not turning over --if turning over try spraying the carb with starter fluid if starts fuel problem --fuel pump --inertia switch --relay-fuel filter --////if no start electrical---//distributor--battery ignition -coil etc the following link shows how to check the inertia switch
How to Check Inertia Switch on Ford Vehicle Fuel Systems and this is link is a free online repair manual which can assist you with repairs
Free Online Auto Repair Manuals and Free Auto Repair Diagrams

ford ranger 1990
If you have trouble in fixing your vehicles, try this link. Very helpful

check your battery cables and connections !

I also have a 2004 Ranger and put in a new starter because all I got was a clicking sound. I did a lot of research after that and it seems the BATTERY doesn't have the cranking amps to turn over the motor. I have it in the shop right now and will know for sure tomorrow but all indications point in this direction.

possible bad connection of engine ground

check the body ground and fuesable link!!!

wrench down on battery connent

Check all connections from the battery to the starter. Also check all grounds. If all else fails take the starter and have it check.

either a bad body ground,or your tranny is locked up,did it run good before you shut it off?

take back to dealer and have them check the neutral safety switch on the clutch because if the switch is not adjusted properly you will have this problem