DMAX Fuel Filter Head Assembly (LLY-LMM) | DMAX Store Brand New Filter Head DmaxStore Note: DmaxStore fuel filter head spacer is recomended when replacing the filter head because it helps keep the filter head cooler and gives you more room to service your filter. Select from drop down from above. Here is an example of the correctly re-routed fuel lines for 2001-2004 LB7 Engines. DIY Duramax Fuel Fix: Rebuilding A Leaky Fuel Filter Head A common problem with high-mileage 2001-2010 Duramax trucks is that the fuel filter head assembly begins to develop air leaks. The engine’s CP3 high-pressure fuel pump is capable of drawing fuel from the tank without the aid of an external lift pump as long as the system remains primed.