Failure mode - Cummins 6.7L ISB Diesel (Ram HD, 2019+ generation)

In-tank lift pump failures (2019+ 6.7)

Reliability tier: verified - verify before ordering, see /disclosure/

Symptoms

fuel pressure sag under load on a gauge; hard hot starts; injector rattle from starvation
CP3 inlet contamination when the pump sheds debris

Compare with the other causes of the same sign on this engine: hard start, long crank or no-start (3 causes) · ticking, knocking, rattle or whine (3 causes)

Root cause

The in-tank lift pump (2013+ layout) remains the 6.7's known consumable: output decays with mileage/heat, and a starving CP3 shows up as injector noise and power fade.

Diagnosis

fuel pressure gauge at the CP3 inlet - log hot and under load
inspect the water-in-fuel filter element and drain schedule

Fixes

replace the lift pump/module and the fuel filter; consider a gauge if not fitted ()

lift-pump - more than one option: 6.7L Cummins In-Tank Fuel Pump/Level Module (Mopar 68444767AA, 2019), 6.7 Cummins 2019+ In-Tank Lift Pump Upgrade (Fleece PowerFlo, 2011-2024 application)
fuel-filter - more than one option: 6.7L Cummins Under-Bed Fuel Filter Base, Fleece Spin-On Conversion (2019-2024 pickups), 6.7L Cummins Fuel Filter (Mopar 68157291AA, 2013-2024), 6.7L Cummins Fuel/Water Separator Kit (Mopar 68436631AA, 2019-2020)

Prevalence

common