FASS 2011-2014 Duramax 6.6L Titanium Signature Series - 165GPHFASS 2011 2014 Duramax 6. 6L Titanium Signature Series 165GPH FASS Fuel Systems Diesel Lift Pump 2011 2014 GM Duramax Lml 6. 6L Titanium Signature Series 165Gph (TS C11 165G). A FASS Fuel Systems can be a beneficial upgrade for your GM Duramax LML diesel engine, this is because your Duramax doesn't come with a factory lift pump like other diesels. This requires your CP3 injection pump to pull your fuel under a vacuum, adding additional stress to your