low fuel spray at carb 1989 gmc vandura

First try spraying a whole can of carburetor cleaner into carb could be just really dirty. If that does not help replace fuel filter and last thing pump in carburetor maybe bad.

That would be a TBI set-up, sounds like very dirty injectors. They should have a nice cone spray of fuel going threw, no droplets of fuel. Should find somewhere that cleans injectors, or try cleaning the best you can with carb cleaner, then run fuel injection cleaner threw the gas, or just replace them. Make sure you have a clean fuel filter on there and if still having problems check the fuel pressure. It should be 9 to 13 lbs. If it is not it would be either a weak regulator in the TBI or fuel pump.