I changed oil sending unit and pigtail now oil is not pumping
If you only changed out the sending unit and pigtail, you should have oil flowing. Have you checked the electrical connectors?
What steps do you recommend to check connectors
Double check the contacts to make sure they're clean. Here's a test http://www.ehow.com/how_7898711_test-oil-pressure-sensor.html
Looking for a Used C/K 1500 in your area?
CarGurus has 880 nationwide C/K 1500 listings starting at $2,500.
Search Chevrolet C/K 1500 Questions
Chevrolet C/K 1500 Experts