I not used my 4wd much only in the winter so when i put it in 4wd it shifted over, put then after a short distance i start to here a popping sound so, I have to stop and put it into 2HI can only one help me.

 

*Moved to 2nd Gen Tech*

It sounds like your front axle is not fully engaging. This is a fairly well documented topic.

The problem could be with the vacuum supply to the vacuum switch on the transfer case, the vacuum line between the switch and the actuator (under the battery), a problem with the actuator (torn diaphragm), a stuck actuator cable to the front diff, or a problem with the shift fork or collar inside the passenger side extension housing on the front diff.

Now some of that information above depends on what you have for your transfer case. The 3-button switch on the dash means you have the NV233 transfer case. 4-button = NV236.

That should give you enough information to then search out for more detail.

Let us know what you find!