Okay, you can drive it forever and the battery wont die. But you go to start it and it clicks. (Its on a truck at work, I dont know if all the lights go off when it clicks, or if they stay on) anyway, if the lights go off, that tells me its a bad connection somewhere, if they stay on and it clicks, then its got to be starter related right? Is there anything i'm missing, or has this happened before alot? He (mechanic) says that it will go for two weeks and start just fine, then all of a sudden, it wont, or it could be 3 days later, then it will start. But the funny thing is that when you put a jump starter on it, it fires right up. Is the starter just getting weak do you think? then when there's extra power, it makes it work? or could it be the solenoid? HELP!

 

Its the starter, replace it.

 

Which truck? I see you have two trucks...do you know how old the starter is and where did it come from? I have had intermittant start problems, and they were because my alternator had been flaky..is there any indication of bad charging? Has the Voltmeter acted up occasionally, or do you ever have bad humming or static on your AM radio stations that follows the RPM's of the engine?
When I had problems, the alternator would stop charging for unknown reasons, and I would drive the truck for 15 miles, park it for the day, and come out the next morning to a worn out battery that had just enuf juice to make the starter relay click.

The old trick for prompting a stubborn starter is to tap it( with respect, don't smash the solenoid to pieces)with a block of wood when you suspect it is stuck.

 

Its none of the trucks in my sig, its a truck at work, which is actually an 1994 F150 4x4 with the 302 and auto tranny. once it starts, you can drive it anywhere. We went to start it this morning, and it acted up, the clicking actually is the starter gear meshing up with the flywheel, its like the starter doesnt have enough power to turn it or something, and i'm pretty sure its not the battery, because when it started doing this, they thought it was the battery so they put a new one in, and it kept doing it. well just to be sure they swapped batterys around with another truck, and it still does it. When you put it on the battery charger it will turn the engine slowly if you let it sit for a couple min, and if you leave it on for a while it will start just fine. Now driving it around town, it will be just fine. we drove it today, and it always started just fine. I wonder if it has the same starter as my 85 302 EFI does? We could just swap starters around to see.