| Engine | Ram model years | What it means for owners |
|---|---|---|
| 5.9 12-valve | 1989 to mid-1998 | Mechanical Bosch injection pump; no engine computer running the fuel system. |
| 5.9 24-valve (ISB) | mid-1998 to 2002 | Electronic Bosch VP44 injection pump fed by an in-tank or frame-mounted lift pump. |
| 5.9 common rail | 2003 to 2007 | High-pressure common-rail injection with electronic injectors. |
| 6.7 Cummins | mid-2007 on | Common rail plus diesel particulate filter; later trucks add DEF (urea) aftertreatment. |
Years from Cummins, MotorTrend and DieselHub. Changeover years were split mid-year; confirm with your engine dataplate and VIN.
What makes it different
High-pressure common-rail injection replaced the VP44 for 2003. Injectors are electronically controlled, which gave quieter running and more power, but common-rail parts are sensitive to water and dirt in the fuel.
Maintenance focus
- Fuel filter and water separator service on schedule. See fuel filters.
- Buy fuel from busy stations, and drain water when the warning shows.
- Oil, coolant and valve lash per your manual.
3rd gen front end
These trucks ride on the 2003 to 2009 3rd gen chassis. The 3rd gen steering brace and crossover steering kit are common first front-end upgrades. Lifted trucks look at the double adjustable long arms for 3rd and 4th gen or the 3rd gen 3-inch kit.
Where this comes from
- Cummins: Follow the liter, evolution of the 5.9L to the 6.7L pickup engine
- MotorTrend: 5.9-liter Cummins history and specs
- DieselHub: 5.9L and 6.7L Cummins FAQ
- Vaden: Fuel filter / water separator guide for heavy-duty diesels (PDF)
- Auto Care Association TSB 91-1: Solving winter diesel fuel and fuel filter problems
Last reviewed 2026-10-19. General information only: your owner's manual and service information come first.