Recipe - GM 3.0L Duramax LM2/LZ0 I6 (2020+)
Reliability build
Reliability tier: aggregated - verify before ordering, see /disclosure/
Fuel filter service with a proper prime for the 3.0L Duramax (mode Extended crank / long-crank no-start (air intrusion, check valve, cam wheel)): the #1 self-inflicted long-crank is air trapped after a filter change - seat the housing fully, cycle key-on and let the pump prime before cranking. The same prime routine diagnoses the overnight long-crank (air intrusion / check valve).
Parts
- 3.0L Duramax Fuel Filter Kit (GM 13539108) - filter kit (tp1015) - the scheduled element (qty 1)
- 3.0L Duramax Fuel Filter / Water Separator Assembly (GM 13543066) - water-separator assembly for the wet half of the service (qty 1)
- 3.0L Duramax Drop-In Fuel System / Lift Pump (FASS, 2019-2026 GM 3.0 LM2/LZ0) - if the overnight prime loss persists - the low-pressure side (check valve / lift pump) is the documented culprit (qty 1)
Install order
- key-on prime cycles BEFORE cranking after any filter service - wait for the pump to finish, then start (prevents the trapped-air long crank)
- seat the lower filter housing fully - an unseated O-ring pulls air into the low-pressure side
- replace the water-separator assembly on its interval; drain the water bowl at every oil change
- if the truck still cranks long after sitting 2-3 days: the low-pressure side loses prime overnight (check valve / lift pump) - address before chasing sensors
Expected outcome
Parts budget
About $50-$550 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.