Is there a remote wire on your aftermarket starter (if it is after market)? If so, is it mounted to the correct side of the solenoid and have you checked it's length to see if it's been damaged by exhaust heat?
yes original starter of ford bronco ,you can disconnect red wire on fender relay still runs and tried after market starter does same thing could i have hooked starter wire up wrong on starter
Ok assuming it is a 90 there is 2 solenoids, one on the fender and one on the starter. sounds like you either have the remote wire directly hooked to power (have the remote wire hooked to battery post on fender solenoid) or have the main power cable hooked onto the wrong post on the starter. The big question is is the starter motor only spinning or is the starter actually engaging and turning the engine over. The wiring should go as follows, Battery to positive side on fender solenoid, large cable from fender solenoid to large post on the starter solenoid from the positive side of fender solenoid(same spot as battery is hooked so constant power). Then from the small post on starter solenoid to the opposite on the fender solenoid. Hope this helps.