I have a 91 jeep wrangler. What should I check if the wheels are not getting any power when it is in gear

do you mean it wont go into gear ? if so what gears ? it could be the clutch going out , if the pedal is soft or easy to push down than it probably needs a clutch. next time it wont go into gear try pumping the clutch or putting it from 2nd to 1st or what ever gear it has problems with

does it ever come out of that gear while moving and can you get it into higher gears than 3rd

I would first check the vacuum disconnect on the front axle (dana 30). The vacuum lines often become clogged and/or broken, especially when wheeling a 20 year old Jeep. My solution for my '93 YJ was the cable option which replaces the vacuum one (try Quadratec). This way I had a more positive feeling and no more vacuum issues to worry about.

if the clutch is draging it will be hard to get your gears and they will chrunch going into gear but its most likly to be a gear box problem could be just low on oil or worse it may be the bulk rings and bearings worn out after all its now nearly 20 years old!

Have you tried letting up on the thhrottle at the same time you shift? That takes the load off the gears and allows the shift to freely occur. Good Luck, Ned

you check for miss how is compression

i have a 1988 jeep wrangler 6cyl with 5 speed transmission. I was shifting the jeep and it got stuck in third gear. We opened it up and saw that the linkage is aligned and everything is in place. I dont know what is wrong and what to do next. please help ....

Check your fluid levels, you need to verify that the transfer case has fluid in it. Also, on one of my old jeeps the lever that put it into 4 wheel drive just stuck a litle. After yanking the **** out of it and moving it back and forth, drive a litle then stop and do it all over again.. a few times. it went into 4 wheel drive. this is why you are suposed to engage your 4 wheel drive once a month and drive around the block, just to make sure it gets flid where its supose to. if it doesn't get engaged then the fluid just sits at the bottum of the transfer case and doesn't get up on the gears.

shift tranny from 1st-3rd if engine revs up clutch needs replacing

check the wires on the transfer case mine got melted by my exhaust somehow and i just have learned to deal with it lol.