2008 Duramax Fuel Line Diagram · Official

This line returns unused fuel from the injectors and the CP3 pump back to the tank to help cool the injection components. 2. Fuel Cooler System Installing a lift pump in a Duramax diesel - Hagerty Media

If your 2008 Duramax is losing prime or entering "Reduced Engine Power" mode, check these specific areas: 2008 Duramax Fuel Line Diagram

Since you are reading this for the specific keyword "2008 Duramax fuel line diagram," you likely want the actual GM service manual picture. Here is how to get it: This line returns unused fuel from the injectors