1991 5 speed 2.5 4x4 i turn the key power comes on but will not start,i have to try a few times before it starts.

SOURCE: 1998 cheeroke sport --replaced starter

check the crankshaft sensor....its not the starter relay if its turning over

SOURCE: my 91 jeep won't start...

The Starter relay is bad.

SOURCE: 1996 Jeep Grand Cherokee Laredo starter

This means it is the solenoid. But usually on those the starter and solenoid are one unit. They can be purchased individually, but it is usually almost as expensive as replacing the whole unit.

SOURCE: 2006 Jeep Wrangler won't start

First, make sure you can turn the engine by hand. If you can't then the starter can't turn it either. Have someone else turn the key and look for the source of the click...may be a relay. Go over the starting circuit with a volt meter. Check for power at the starter main terminal and then with the key turned to "start" check for power at the trigger terminal on the starter. Check battery voltage and check relay operation.
You have a neutral safety switch on the transmission if its an automatic and a clutch switch if it's a stick. Check them as well. Make sure battery grounding on fender and block are also clean and secure.

Testimonial: "Will try! Thanks!"

SOURCE: 2007 jeep wrangler tip start feature problem

yes, sounds like the starter solinoid whent out, if it shorts out it can stay running, it must be replaced ,there is no quick fix, if its a manual trans you can push start it. i dont know of any internet tips.