Need to replace a fuel filter on 89 buick century

Replace the fuel pressure regulator

I dont know if 89 Buicks are fuel injected or carburated. If it has a carburator, there may be a problem with the choke.

Is the pump getting power from the fuel pump relay ?

Did you check for spark? It sounds like you're not getting spark. Check for spark. If you are not getting spark then it sounds like you might have to replace the coil packs. Is it running a L4 engine? If its running a standard chevy L4 its probably the coil packs. Try to replace them check again for spark.

it seems more fuel related--maybe air in line or fuel pressure regulator got vaccum disconnected--u may hav disturbed a wire or somethin too

You have a fuel starvation problem, fuel pump, pressure regulator, injectors, any or all of them could be the reason why you are not getting fuel. Someone is going to have to lay hands and eyes on the thing and check it out.

Should be located behind the harmonic balancer on the bottom of the motor. You'll need a balancer puller to remove it.

sounds lik either a fuel filter plugged or the cat is plugged, check fuel pressure or just replace filter and if that isn't it have a muffler shop check the exhaust for excessive back pressure.

You definitely covered most of the bases. Considering all you've done so far, I would check into the fuel system next. First, how old is the fuel filter? Has it been changed? Yes, a bad filter can cause the problems your having. Next would be the fuel pressure regulator. You need a fuel pressure gauge to check it, which you should be able to rent from a good auto parts store. That will also tell you how good your fuel pump is, i.e. if the pump can deliver the necessary fuel pressure off idle. After that, I would check the injectors themselves for wear or blockage. A bottle of fuel injector cleaner in the gas tank would be a good idea, cheap, quick, and it wont make anything worse. If all that checks out, check your catalytic converter, a clogged or bad cat will also do what your describing. Good luck.

Check fuel pressure after replacing filter. Fuel pump may be going bad.