1990 F150 351 starting problem. Lower intake was leaking oil. It had leaked quite a bit of oil on the starter so while truck was in the shop having gaskets replaced I had the starter replaced as preventative maintenance. After I got truck back it started around 12 times better than ever with no trouble. Then one day I got in truck and it did nothing but click. When i jump the solenoid I can hear the solenoid click as well as hearing a click at the starter as the gear drive engages the flywheel, also hearing what I'm guessing could be a rely click on the driver side fender well. I can turn motor over with a ratchet. It has a one wire starter with engine comparment mounted solenoid. Took new starter back and got a second new starter. Same problem, it just clicks. Replaced solenoid, and nothing but click. New battery, click. New battery with jumper cables, click. Checked all connections for corrosion and loose connections, all fine. Installed used oem starter, click. Any ideas???

FIXED!!!!! Ended up being an issue with one of my grounds

 

Corroded ground for sure. Fast way for others to check without tools is to go from the neg terminal on the battery to the block with a jumper cable.

Adrianspeeder