i am not fully understanding what you are saying. you had to ground the solenoid. what post did you have to ground? you shouldn't have to run a ground from any of the posts on the solenoid.

the Ford solenoid is a pretty simple device. the two large copper posts go to the battery (+ side) and the other one goes to the starter. there will be a couple of other wires attached to the positive side, these are for main power and battery charging.

depending on the solenoid you will have either one or two small terminals marked S and I (if a two post version).

the S terminal goes to the start position on the ignition switch and sees 12v during starting while the I terminal goes to the + side of the coil to give it a full 12v when starting, then when started the coil gets power thru the on position of the ignition switch at a reduced voltage. not all vehicles are wired this way so the I is not always used.

the body of the solenoid is the ground path so you have to make sure that there is a good ground between the metal mounting tab and the frame or whatever you have it mounted too.

if youhave to ground one of the terminals, something is wrong with your wiring.

rgds
Mike