LML Injector Return lines keep failing. - Chevy and GMC Duramax Diesel . . . However, I am concerned that I may have some blockage or a bad return pressure regulator or maybe something related to the CP3 conversion The return line regulator is part of the harness i ordered, but I would like to do some testing to rule out or isolate the cause
6. 6L Duramax LML Fuel Return Testing - Diagnostic Network It seems to me that it should be a valid and safe test to block the return line from the pump (steel pipe), and run the injector return (rubber hose) into a container, then attempt to start the engine
Duramax LLY Injector Return Line Issues Fix - Ron the Parts Guy While repairing just the leaking section might seem economical, it’s often a temporary fix The LLY injector return lines are known to degrade over time, and if one section has failed, others may not be far behind
Duramax LML Problems: 10 Common Issues Real Fixes (2011–2016) LML Duramax guide: CP4 fuel system risk, DEF NOx sensor headaches, turbo control issues, boost leaks, overheating, and Allison strategy—plus proven prevention steps and upgrade paths
2016 Silverado 2500 Duramax Won’t Start After Fuel Repair One of the most common issues I encounter with no starts after a fuel system replacement on an LML engine is the possibility of the FPR1, FPR2, and Fuel Temp connectors being mixed up Since the connectors are identical, if they are incorrectly plugged in, they won't trigger any codes
LML LGH Duramax Injector Return Line Assembly (2011-2016) If the pressure is low and there are no leaks in the fuel return hose assembly, the most likely cause is the return line pressure regulator which is part of the return hose assembly