I have a 2000 jeep xj ill go out and crank on it over and over again but it wont fire... other times I can go out and it will start up no problem. I can hear the fuel pump priming.. Could it be cause by a clogged convertor?

 

Not likely.

When it doesn't start check for spark at the plugs. If nothing, check coil. If nothing, check CPS.

Also verify pressure at the rail with a gauge.