First off its a 99 f150, 4x4, auto, 4wd with 150k on her, and the 4.6.

So I've been having these problems with the truck starting every so often. Turn the key, and you hear a click. So, I bypassed the relay on the firewall, and I hear the click from the starter solenoid down on the starter...ok why isn't it starting. Battery and starter are around 8-10 months old.

I've had this on going problem for around a year now off and on. It will fight with me for a week, then fine for 3 months. Acted up last wednesday, got it started after trying various times over a few hours, then she finally started. Was fine until last night, had trouble getting to start couple times.

Any help will be greatly appreciated, just wish the problem was consistent

 

if it were me i would have the battery checked and make sure the terminals are clean and tight.check for loose wires at the terminals.

 

Battery is only 6 months old, 900 CCA.... should still be good, wouldn't hurt to check it. Either way wouldn't explain why it only happens every so often. Terminals on battery seem good, connections down on starter and solenoid look as good as they can get in NNY.

 

If it were me, i'd run a extra ground from battery to block. See if that helps

 

Reexamine the wires at the starter for corrosion. The corrosion wicks up the wire and creates resistance. So much so that the starter lacks enough power to start. It just clicks.