Recipe - Cummins 6.7L ISB Diesel (Ram HD)

Reliability build

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

Fuel-supply health for a 6.7 Cummins on the CP3 common-rail (mode Lift pump / fuel delivery weakness): filter discipline, a healthy lift pump and a fresh FCA are what keep a $3-4k injection system alive. Most 'dead injectors' reads start as fuel starvation.

Parts

6.7 Cummins Fuel Filter Set (water separator + engine) - water separator + engine filter on schedule; water discipline is injector/pump life (qty 1)
6.7 Cummins In-Tank Lift Pump (stock type) - stock supply pump; catalog PN 5145571AA covers rows 2011-2020 - pre-2011 trucks need VIN confirmation (qty 1)
6.7 Cummins Fuel Control Actuator (FCA, on CP3) - Bosch FCA/MProp on the CP3 - a failing FCA mimics a dying pump; swap before condemning the pump (aftermarket MPN, aggregated tier) (qty 1)
6.7 Cummins Injector Seal/O-Ring Kit - seals/connector tubes while fuel side is open; blow-by soot at the tubes reads as injector failure (qty 1)
6.7 Cummins Lift Pump System (high-flow upgrade) - frame-mount/in-tank upgrade path for towing or tuned trucks; era coverage varies - see the part disclosure (qty 1)

Install order

both fuel filters, drain the water separator; log water-in-fuel frequency
test fuel supply pressure at the CP3; low/erratic -> lift pump or FCA
FCA swap before pump replacement if pressure is erratic at idle but recovers
replace the supply pump if pressure stays low under load
optional: upgrade pump for sustained towing/tuned use; verify era applicability first

Expected outcome

Stable CP3 inlet pressure across load; no water-in-fuel recurrence; smooth idle.

Do not

do not chase injector replacement before proving supply pressure at the CP3
do not keep driving with water-in-fuel warnings - water past the CP3 is a $3-4k mistake
do not pre-fill filters with non-fuel liquids; fill with clean diesel only

Parts budget

About $80-$860 in parts. It depends on what the diagnosis finds; each option below is what you buy together. Prices marked "at Dave's" are Dave's Auto Center's, the same as in his store; the others are approximate prices from OEM and maker catalogs, rounded (a manufacturer's list price can run higher). Parts only, no labor.

about $80: 6.7 Cummins Fuel Filter Set (water separator + engine) (about $80)
about $380: 6.7 Cummins In-Tank Lift Pump (stock type) (about $380)
$829.95-$851.95: 6.7 Cummins Lift Pump System (high-flow upgrade) ($829.95 at Dave's)

DIY or shop: All DIY with hand tools; the filter head is the fiddliest part.