1991 jeep wrangler will not go into 4 wheel drive

SOURCE: Vacuum lines for 4 wheel drive

if you look under the Jeep on the passenger side of the front axle you will see a vacume mod its kind of round shaped it should have a vacume plug on it wit ha few hoses going into it make sure its plugged in for starters these come off all the time if it looks good here simply follow the lines into the engine compartment and look for broken hose this should get you a fix most of the time, the mod could be defective but not likely.

SOURCE: 4wd problem jeep wrangler yj 1995

i just bought a used 97 CHEROKEE but i had the same problem, when i got to looking at it i found out the front driveshaft was shot, look at that, if its not it i would say its probably the transfer case especially with an older vehicle like that which is a very expenxive repair

SOURCE: 1991 jeep wrangler: alternator overcharging

It sounds as the voltage regulator which is built into the back of the alternator has stuck. Occaisionally this even happens on new ones. Would suggest taking the alternator back as it shoud be under warranty.

SOURCE: 1991 jeep wrangler clutch

Is there a very short term solution? I just want to get the jeep from my Dad's house home and I don't want to have it towed. Once i have it at my place I can do the more extensive work.

Thanks

SOURCE: 4 wheel drive doesnt work.

Has this Jeep been modified at all?
It sounds like the shifter cable was reinstalled backwards.
Specifically the 4-Low "Not Climbing Well". 4-Low should give you the best torque and hill climbing ability.
Do you feel any "Binding" in the steering wheel (difficult to turn)?
Remember a Jeep uses real driveshafts and differentials to give you 4WD - you cannot engage 4WD or 4-Low on dry hard surfaces. It needs a little bit of slip between the wheels for turns.
Check you're fluids too.