For the third time and the third solenoid my truck won't start. What could be wrong with it this is really getting old it just clicks but won't turn over I fix it but eventually it happens again,

 

are your cables, battery, and alt in good shape? sometimes the solenoids get stuck (either in engaged or disengaged) when the battery is not charged properly. if you dont have a maint. free battery, it wouldnt hurt to check the distilled water level.

 

Start at the batt. load chk it and alt. too.(auto zone etc.) check your cables , a loose or coroaded ground cable will do the same thing. check all wired connections make sure there clean and tight. Make sure your getting 12V from the key switch at the solenoid. maybe a problem there. ( jump the siolenoid) check the starter tap on it with a hammer maybe theres a bad spot in it. An intermitent problem can be a bear to narrow down sometimes, good luck.

 

Had similar problem on another vehicle - turned out all that was wrong was a bad pos battery cable. couple of bucks - well, back in the early 80's anyway.