ive checked every vacume line there is and i still havent found the problem. you can push the 4hi button and hear it click but it still doest pull!!

 

Here is a simple test for the axle engagment;
Remove battery and pan, lift right front wheel off ground, connect Ohm-meter to axle switch.

Note switch should be "Open" or very high Ohms. Turn wheel and notice feel and observe front drive shaft. Wheel should turn free and drive shaft not turn.

Now pull 10 in of vac on front engage diaphragm with hand vac pump. Notice if vac holds or bleeds quickly.

Switch should now be closed or very low Ohms.
Turn wheel and notice feel and observe front drive shaft. Wheel should show more drag* and front drive shaft should now rotate with wheel.

Now, release vac below 2in. All conditions should revert to original.

*Note; If TC is in 4W position, then engaging the front axle will stop the front wheel completely.