I have 1989 b2600i. Once the truck runs for 1 or 2 minutes the dashboard oil light comes on. I replaced the oil pressure sending unit on the side of the block and it did not help. I am not sure what the oil pressure is suppose to be. Does anyone know? Is the easiest way to check it by putting a gauge where the sending unit is? I saw a picture that shows there is a strainer in the oil pan. Is it possible this is getting plugged? Any other ideas?
Thanks in advance
Dave

 

Oil pressure at idle is 16-30 psi and 44-58 psi at 3000 RPM. I would try a mechanical gauge where the sensor goes to verify.

I would consider dropping the pan and checking the oil pickup screen. I have had many vehicles in the past with this same problem and thats what it was. I had to remove the screen and clean it along with the pan that gets carbon build up on the bottom because it gets sucked up on the screen