1992 4.0 cherekee. the idler pully bearing went out and at the same time the motor started running bad and it smells like its flooding with gas could ot be the alternator?

Sometimes the A/C clutch pulley goes bad. It is a combination of a clutch and an Idler pulley. This means the part is always turning the bearing regardless of whether the A/C is on or off.

But you can try to change out the tensioner and idler to see if they help. Parts vary widely in price.

As for A/C pulley, some are removable without taking off the compressor. They have left-hand thread and a small clip. Require grinding out bearing assembly and punch pinning new part to hub. Often can be done in an hour by the ambitious.

Would think that roughness in bearing as you checked could be judged as good or bad.

COULD BE A BAD BEARING IN THE IDLER PULLY OR THE TENSIONER ON THE TIMING BELT OR THE SERPENTINE BELT. IF ITS A SQUEEL IT MAY BE SOME COOLANT GOT ON THE SERPENTINE BELT. TRY TO WASH THE BELT WITH WATER AND LET DRY COMPLETELY. IF NOISE REMAINS RETURN TO THE SHOP THAT DID THE WORK.

Just an idler, probably has a frozen bearing, you will need to get it repaired.

You have a bad fule pressure regulator to check to see if this is the problem look on your fule rail and you will see a round piece that has a vaccume line on it start car and un plug the line if gas is comming out of the regulator its bad. it floods the motor with gas it drives ok because you are hitting the gas and it allows more air in to compensate for the xtra fule, but once you let off gas its flooding out. Thats why you smell it and all the black smoke. hope this helps.

Alternator bearings a possible. Idler Pulleys or Belt Tensioner Pulley

Sounds like your drive belt is slipping, it is either worn out or needs adjusting. You may near it louder when turn your steering wheel.

1999 probably has a serpantine belt (multi grooved). I would guess that you may have a squeaky belt or more likley a bad bearing in on of the idler pulleys. Remove the belt and spin the idlers by hand. If one feels rough or makes noise replace it.

Could be several things. WHICH ENGINE?.. 4 cylinder (has three belts, power steering/water pump, alternator & A/C compressor, one tensioner pully A/C compressor), The V6 2.7 (has only one belt, 1 Idler pully and 1 tensioner pully), the V6 3.5 has two belts - A/C/alternator, and power steering - there are two tensioner pullys). Noises can be caused by the belt(s) themselves, pullys, bearings, pully bearings, water pump shaft bearings (or belts/pullys rubbing up against something). Let's not forget that there is also belt(s) behind the Timing Belt cover as well as pullys and bearings associated with the timing system. You could start by removing one accy drive belt at a time (alternator, water pump, compressor, power steering, etc) to see whether or not the noise goes away in each case. If after each case, you discover the noise is still there, it's probably behind the timing belt cover (idler/tensioner pully, water pump shaft bearing, crankshaft bearing, etc.). Good Luck

check the idler/tensioner pully's and the alternator pully, there is a common problem with one of these 3 going bad, usually an idler pully the best way to check is to get a mechanics stethescope and touch the end to the bolt on the idler pully's you will notice a very distinct sound difference from a smooth pully and one with bad bearings. gm tech here, seen many of these

hi check your drive belts and make sure that none of your idler or tenshioner pullies have not frozen up.and chack to make sure that your ac compresor is not frozen.