2001 F250 7.3 diesel
No turn over - 1 click selenoid engages but no spin on starter.
Grandpa says heard a pop or short sound when tried to start first.
Replaced:
- ignition starter switch under steering column
- solenoid on fender well
- nuetral safety switch
- 2 new starters.
- 2 batteries

Verified :
- can hand turn motor not hydro locked.
- 12.5 v to solenoid on brown w red wire from nuetral safety to solenoid when key in start
- 11.6 v to starter on main battery cable
- 12.5 in new direct wired jumper from solenoid to starter
- solenoid click only in park and nuetral ( assume good nuetral safety switch)

Will not start by direct shorting solenoid
Will not start by direct shirting the starter
Starter will engage/spin out of truck but will engage no spin hooked to truck free and dropped

 

How hard was it to turn over manually. Start watching below video at about the 8:10 point. Maybe something a little outside the box???

 

when you say "hooked to truck free and dropped "are you say hot wire hooked up but starter not mounted. I may be wrong but believe the starter uses the block as ground so if its hanging free you have no ground.

 

Good point - yes you understood. Loopy after several hours trying to pinpoint what should be so simple!

 

If there was a "pop" you might have blown a fuseable link in the wireing. They are actually in the wire itself and just look like a bulge in the wire. Only way I know to test it is to isolate the wire and check for continuity.