Short answer
The Bosch CP4 high-pressure fuel pump was used on several modern pickup diesels, including the LML Duramax, the 6.7 Power Stroke and the 3.0 EcoDiesel. Class-action lawsuits against Ford allege that the pump can wear internally with U.S. diesel and send metal debris through the fuel system, damaging injectors and lines. Those are allegations in court filings; the takeaway for owners is to keep fuel clean and dry.
Start with the easy checks
- Change fuel filters on schedule and drain water.
- Buy fuel from busy stations.
- Act on any water-in-fuel warning right away.
- If the truck stalls and will not restart, do not keep cranking; have it towed for diagnosis.
Likely causes, most common first
- Water or contamination in fuel
- Harmful to high-pressure pumps.
- Air or low supply
- Starves the pump.
- Internal wear
- The subject of the lawsuits.
These are common causes, not a diagnosis. The same symptom can have a different cause on your engine; codes, tests and your service information decide.
When to stop and see a diesel tech
- Metal found in the fuel filter.
- Sudden stall and no restart.
Questions
Which trucks use the CP4 pump?
Sources list the LML Duramax, the 6.7 Power Stroke and the 3.0 EcoDiesel among pickup diesels with the Bosch CP4 family pump.
Related symptoms
My water-in-fuel light came on. What should I do?
Troubleshoot →Fuel systemCan a plugged fuel filter cause low power on a diesel?
Troubleshoot →StartingMy diesel cranks but will not start. Where do I begin?
Troubleshoot →Where this comes from
- U.S. District Court (E.D. Mich.): Droesser v. Ford, CP4 pump opinion
- Nunez v. Ford amended complaint (CP4 allegations, PDF)
- RealTruck: Duramax engine generations
- DieselHub: 3.0 EcoDiesel
Last reviewed 2026-10-19. General information only: confirm with your service information and a qualified diesel technician.