Originally posted by Sammyprgandy
I have an '87 Ford F-150. I just replaced the alternator,battery and selenoid. I did that because something was draining the battery. Now,I hook up the positive to the battery and it gives a spark,starts welding the clamp to the post and begins to start the motor...even with the key in the off position! I let it start with the key in the on position and disconnected the positive,and the alternator would not hold the motor. What do I look at first?
Go back to your solenoid that you put on, sound like the starter wires are hot all the time. If it wont doing that until you worked on it go back over what you did. the alt is not going to make the starter to turn over.