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CP4 pump failure — symptoms, what it costs and the conversion fix

The Bosch CP4 high-pressure pump can fail by scoring its roller and cam, sending metal through the rail, injectors and lines; the symptoms are a long crank, low rail pressure codes, stalling and metal in the fuel filter. Diesel Fuel Injection Service in Scappoose, Oregon sells the S&S Diesel Motorsport and Alliant DCR conversion kits and CP3 conversions that replace the CP4 for good on 2011–2025 6.7 Power Stroke, 2011–2016 LML and 2017–2025 L5P Duramax and 2019+ Cummins 6.7. (503) 235-1947.

Signs of a CP4 failure

  • Long crank or no start, especially warm
  • P0087 / low rail pressure, P0088 spikes, limp mode
  • Fine metal in the fuel filter or on the rail screen
  • Fuel system flushed once already and the problem returned

What a failure costs — and why the conversion is cheaper

  • A failed CP4 contaminates the entire high-pressure side: pump, injectors, rail, lines and filters all get replaced
  • A DCR or CP3 conversion fitted before failure, or with a new set of injectors after one, removes the CP4 design from the truck
  • Pro Automotive & Diesel in Scappoose installs the conversions we sell; see their L5P and 6.7 Power Stroke DCR pages for installed pricing

Questions

Ford 6.7 (2011–2025), Duramax LML (2011–2016) and L5P (2017–2025), Ram 6.7 (2019+); give us the year and we confirm.

The DCR kits we sell are CARB EO-listed for the applications they cover; ask for the EO number for your truck.

The kits are complete except for a few OE gaskets and the drive gear on L5P; we list those with the kit.

Our sister shop Pro Automotive & Diesel next door does, (503) 987-4000.