Your lift pump is the most overlooked component in the diesel fuel system — and when it fails, it takes your injection pump with it. Learn how lift pumps work, the 4-stage failure cascade from low pressure to catastrophic injection pump damage, warning signs to watch for, and whether to go OEM replacement or upgrade to FASS/AirDog. Covers Cummins VP44, Duramax CP3/CP4, Powerstroke, and agricultural applications.