Quote Originally Posted by frank.williams741 View Post
What is the plugged return orifice in the tank? I am working on my father-in-laws 03 Duramax with fuel in oil issue. Replaced all injectors, just replaced cp3 pump and same issue. It has put roughly 2 quarts in less than 50 miles. Also it has a slight hazy smoke at idle. Other than the fuel in oil issue it is a great running truck. He bought it used a few months ago with 107k miles and didn’t catch this issue. I want to see if the return orifice you refer to could be the culprit before we tear back into the motor. Thanks!

My first question is where did the pump and injectors come from? Haze at idle points towards injectors.

The plugged return line scenario is exceptionally rare. There should be nothing in the system large enough to block it. You can try blowing back through the return line and see if it blows bubbles in the tank. Just be sure to keep psi low.