random starting problems

Ok, I have a 90 cherokee that is all stock under the hood except for the upgraded cooling.
# times now it fails to start. I can hear it clicking in that little metal box thing on the side fendorwell, but wont turn over. I tried tapping it a few times and it started once, ran fine. I shut it off and about an hour later, it wont start again. SOOOOO, what is that little box thing and is that the actualy problem?? or a flewk??

1990 cherokee
Stock Renix 4.0 inline 6
Rustys 4.5 lift
HD steering, Lokrite locker front
Ford 8.8 rear with disk brakes

the box is a relay. if it worked after smacking the relay, then you probably have a bad relay. did you smack the starter? they will sometime get bad spots on the comuntator or the brushes get worn and smacking it will sometimes kick it off. thats why i ask. but i think you ment the relay, they are cheap. of course its hard to tell %100 percent from a post but thats probably what it is.

If the relay was clicking and the starter was not engaging, then likely you have a bad starter.

If the relay clicked a few times, then stopped clicking just before you smacked it, then its likely the relay.

the relay is lightly clicking. By tapping on the relay, it startes the vehicle just fine. The starter does not drag or anything. I am going to pull the relay off my parts jeep and see what happens since nobody has one in stock. Thanks once again for the fast replies. I am learning alot and soon hope to post assistance to those in need.
Like on a ford 8.8 swap, I done it and it works GREAT!!!!!

Laterz
:doh:

ok, well after trying to find the correct relay, I finally found one by going through all the boxes on the shelf at the parts store. It sure is NOT the one that the dealer or any other parts store calls for. I replaced it and tried to start it and...............................WAIT FOR IT........................ YUP you guessed it, NO START!!!!! AAAAAHHHHHH I hate these types of problems.
So, anyway, I will try and tap the starter tomorrow and see if it starts. My only other concern is that the ignition key on the steering column is REALLY hard to move sometimes.

UPDATE!!!!!!!

I took the starter out and had it tested, it works. Took battery and had it tested, its good. Replaced starter relay and it does same thing. Tried starting in nuetral and same thing.
I get fuel pump prime, clicking in relay but nothing at the starter.

NEED HELP PLEASE!!!!!!

FIXED FIXED FIXED FIXED!!!!!!!!!

Turned out to be a bad wire crimp on the SOL wire on the relay to the starter solanoid.
New .03 cent end and it works again.

Sweet. Thanks for letting us know the final problem and fix.