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Call or Text (352) 722-5295Fuel system on the 2019-2024 Ram 6.7L Cummins
Fuel starts at an electric lift pump inside the tank. It pushes fuel through a frame-mounted water separator, then an engine-mounted 3-micron NanoNet filter, and on to the high-pressure pump. On the CP4.2 there is no gear pump, so the in-tank pump does all the supply work and primes the system when you turn the key to run. From there a Bosch common rail feeds solenoid injectors at up to 29,000 psi, up from 26,000 psi on 2007-2018 trucks. Ram fitted the Bosch CP4.2 on 2019-2020 trucks and went back to the CP3 for 2021-2024. The 6.7L Cummins in this generation is approved for ULSD and biodiesel blends up to B20; going past that limit risks corrosion inside the fuel system.
What fails and why
The CP4.2 is the fuel story of this generation. When one fails it sheds metal into the rail, injectors, lines and even the tank. Watch for ticking, loss of power, stalling, a no-start, or metal in the fuel filter. It can happen at any mileage; many fail near 100,000 miles, but earlier failures are common. FCA recalled 222,410 trucks from the 2019-2020 model years under 21V-880 (Y78). The fix installs a CP3 in place of the CP4, reflashes the PCM and inspects the fuel system. Because the metal lodges downstream, a CP4 failure usually condemns all six injectors, and the factory procedure replaces the lines and rails along with them. Some owners of 2019 trucks report misfires and rough running after the retrofit, and contamination left in the system is the usual suspect. Separately, recall 19V-498 covers 2019 fuel lines that may leak fuel into the engine compartment; a fuel smell or a visible leak is the sign. Water and wrong fuel are the other threat. Both pumps rely on the frame-mounted separator, and at least one dealer traced a DEF warning on a 2020 3500 to diesel contamination, a reminder that mis-fueling happens.
Stock replacement vs. upgrade
Start with maintenance. Change both fuel filters every 15,000 miles or 12 months, drain the water separator routinely, and look for metal in the old filter when it comes off. After filter service, cycle the key so the in-tank pump primes before you crank. A lubricity additive at every fill, one that is safe for the DPF and SCR system, is the standard preventive step on a CP4 truck and harmless on a CP3. If you own a 2019-2020 truck with no record of Y78, get the recall done first; it is free at the dealer. The most common upgrade is a frame-mounted lift pump and filtration system. AirDog and FASS build units for the 2019-2024 Ram 6.7L that steady supply pressure and pull water and air out of the fuel before it reaches the CP3 or CP4.
What we carry
For lift pumps and filtration: FASS Titanium Signature Series and Drop-In systems with their water separator and particulate filters, AirDog FP-4G, II-5G and Raptor 4G systems, the BD Diesel Venom lift pump, and the G&R Diesel CAT filter conversion. For injectors: new SO and HO sets from Dynomite Diesel and Exergy Performance, plus connector tubes, feed tubes, seal kits and hold-down bolts from XDP, Exergy and S&S Diesel Motorsport. On the high-pressure side: an XDP remanufactured CP3, S&S pumps and CP3 conversions, and Exergy rails, rail pressure sensors and fittings. Fleece Performance Engineering covers SureFlo sending units, an under-bed filter assembly and a dual pump pulley, XDP sells tank sumps, and PPE makes billet fuel and DEF caps. For treatment, browse fuel additives from Hot Shot's Secret, Lucas Oil, Exergy, XDP and Merchant Automotive.
Fitment notes
On this platform, model year decides almost everything. A 2019-2020 truck may still have the CP4.2 or may carry the CP3 from the recall, and pump parts, calibrations and fuel-system kits must match what is actually on the truck. That is why FASS lists separate kits for 2019-2020 and 2021-2024, and why Dynomite splits its injectors into 2019-2021 and 2022-up part numbers. Injectors are also listed by output: SO for the 370 hp engine used in the 2500 and 3500, HO for the high-output engine offered only in 3500 pickups with the Aisin AS69RC. The frame-mounted water separator changed for 2019, and ordering the 2013-2018 part is the most common mistake; the engine-mounted filter is the same from 2013 through 2024. Tank size depends on cab and bed, with 31 gallons on crew-cab short beds, so sending units and sumps must be matched to the tank. On 2023-2024 Rebel trucks a factory skid plate protects the tank and transfer case, so plan around it for under-truck installs. These parts are for 2019-2024; the 2025 trucks moved to a CP8 pump rated to 39,000 psi. Verify by VIN before you order.
Frequently asked questions
How do I know if my 2019-2020 Ram still has the CP4.2?
Check whether recall Y78 (NHTSA 21V-880) shows as completed for your VIN. The recall replaced the CP4.2 with a CP3, reflashed the PCM and inspected the fuel system. If there is no record, have the dealer do it first, since it is free. Then order pump parts to match the pump that is actually on the truck.
How often do the fuel filters get changed on a 2019-2024 6.7L Cummins?
Both filters, the engine-mounted 3-micron NanoNet and the frame-mounted water separator, are on a 15,000-mile or 12-month interval. Drain the separator routinely between changes and check the old element for metal. After the swap, cycle the key to run so the in-tank pump primes the system before you start it.
Will a 2013-2018 water separator fit my 2019 Ram?
No. The frame-mounted separator changed to 68436631AA for 2019, and the 2013-2018 68197867AB will not fit. It is the most common wrong order on these trucks. The engine-mounted filter, 68157291AA, is unchanged from 2013 through 2024.
Do I still need a fuel additive if my truck has the CP3?
The standard recommendation is a DPF- and SCR-safe lubricity additive at every fill on CP4 trucks, and it is harmless on a CP3. ULSD lubricity is the leading theory behind failures of roller-follower pumps like the CP4. In extreme cold, add an anti-gel treatment too.
Why replace the injectors after a CP4 failure?
A failing CP4.2 sends fine metal into the rail, lines and injectors. That contamination usually condemns all six injectors, and the factory repair replaces the lines and rails along with them. When owners report misfires after the recall retrofit, contamination left in the system is the usual suspect.
Not sure what fits? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell.