okay here we go again seems like once maybe twice a month something goes wrong on this truck 1989 blazer 4.3 2 door 4x4 okay it locks up when you try to start it and it has low oil pressure im thinking low oil or maybe oil pump what do you think but honestly the truck should have a warning labile

 

Oil pressure problems can first be solved by checking the oil level. I'm sure that's not the problem, if you have problems with oil pressure it's probably the pump. The oil pump could be damaged or the bypass vavle stuck open. The oil pump for the older small block chevys and 4.3's are ran off the distributor, a new pump should run about $20 to $50.

Make sure it is the pump by doing an oil pressure test with an external oil pressure gauge. You can get one from the auto parts store, just remove your vehicle's oil sending unit and screw in this gauge it will tell you everything.

My truck runs at 20 to 25 PSI hot at idle and 60 PSI cold at idle, your truck shouldn't be too different.

Also, and hopefully this isn't the case, but your engine bearings may be done for and you'll need an engine rebuild. If get the oil pump out, remove one of the bearings and check it out. If it's badly worn it's time for an engine rebuild.