have the 5.2l 318 cid have replaced the fuel pressure regulator, fuel pump, fuel filter, all fuel lines have been replaced or cleaned out and can only pull 10 psi yet its blowing black smoke code 52(sustained rich air/fuel ratio condition detected in O2 sensor bank position 1) has any one had this problem please help

 

what year is it?

 

carb or TBI? I have to assume it is newer than our trucks if it has dual O2 sensors that track bank 1 and 2.

 

the truck is a 1989 and it is tbi

 

First. How does the truck run? You may have a bad O2 sensor or your intake may be restricted. I don't understand how you can know it is bank 1 when our trucks only have one O2 sensor but here is what I do know. I would check the spray pattern of the injectors by looking in the throttle body while the truck is running to see if you are dumping fuel into the engine. You should see a cone spray pattern with no solid streams. If you do not have a good spray pattern you can try fuel system cleaner but if that doesn't work the injectors will need to be replaced. If you have a good spray pattern and the O2 sensor is OK then you are not burning the fuel properly. (timing, bad plugs, wires, coil)
I assume since you gave us a low fuel pressure (10 verses a normal 14.5) that you have teed into the fuel supply line feeding the TBI. Use a pair of pliers and momentarily squeeze off the return line from the TBI to the tank. The pressure should rise to 50 PSI. If there is no pressure increase and you have replaced everything you said the only thing left is the strainer sock that protects the pump in the tank. These socks can get hard with age and restrict flow to the pump.