2003-2004 Dodge 5.9L Cummins Lift Pumps

Lift pumps on the 2003-2004 Ram 5.9L Cummins

The 2003 model year moved the 5.9L Cummins to Bosch high-pressure common rail with a gear-driven CP3. Fuel leaves the tank, gets pulled forward by an electric transfer pump mounted on the fuel-filter canister facing the back of the engine, passes the Fleetguard FS19856 filter, and reaches the CP3. The lift pump only makes about 10 psi to the filter. The CP3's internal gear pump raises that to 80-180 psi before the fuel control actuator meters it into the pumping chambers. For 2005, Dodge moved the lift pump into the tank, so 2003-2004 pumps are their own part.

What fails and why

The factory pump is a wear item. Expect 80,000-120,000 miles from one; Diesel Hub puts the expected life around 100,000. When it goes, you get a no-start or a truck that won't run, low fuel pressure under load, and hard starts when the engine is hot. A healthy pump should still hold about 5 psi at full power, which is why a fuel-pressure gauge earns its place on this truck. The gauge taps in with a 12 mm banjo snubber at the CP3 or the filter housing, and the snubber keeps pump pulses from wrecking the sender or making the needle jump. One piece of good news for 2003-2004 owners: a dead lift pump will not harm the CP3. The truck just won't run until the pump is replaced.

Stock replacement vs. upgrade

Dealer parts counters no longer sell the external pump for these trucks. What they sell is a kit that relocates the pump into the tank. We'd rather see a stock truck keep an OEM-style external pump on the engine, because it keeps a roadside swap possible, and that's the route the replacement pumps on this page take. The math changes if the truck runs compliant upgrades that add power. TDR found the factory pump may not be adequate for much more than 60-70 hp over stock. Past that, the standard fix is a frame-mounted pump and filter system with 2-3 micron filtration and water and air separation. It pushes fuel forward from the back of the truck instead of pulling it the full length, and it keeps the pump out of block heat. Browse the full lift pumps category for those and confirm 2003-2004 fitment on each one.

What we carry

On the stock-replacement side, BD Diesel offers the 1050231 OEM Replacement Lift Pump, listed for 2003-2004.5 Cummins trucks, and Alliant Power offers the AP4089602 Fuel Transfer Pump Kit, built for the 2003-2004 5.9L. Both replace the factory transfer pump. BD also makes the 1050226 Auxiliary Lift Pump, listed for 1998.5-2007 Cummins trucks; read its product page for how it installs on a common-rail truck before you order.

Fitment notes

Year matters more than anything on this page. 2003-2004 trucks carry the lift pump on the engine and 2005-2007 trucks carry it in the tank, so pumps, kits, draw straws and sumps don't cross over. Mid-2004 Cummins 600 trucks still have the engine-mounted pump, which is why you'll see listings that read 2003-2004.5. The exception that catches people: a 2003-2004 truck that already got the Mopar in-tank relocation kit now needs 2005-style parts. Look at the filter canister before you order. If the pump isn't there, call us. When in doubt, verify by VIN.

Frequently asked questions

How do I know the lift pump on my 2003-2004 Cummins is going bad?

Watch for a no-start or a truck that won't run, low fuel pressure under load, and hard starts when the engine is hot. A gauge settles it: a healthy pump should still show about 5 psi at full power. Most factory pumps last 80,000-120,000 miles.

Will a dead lift pump ruin my CP3?

Not on 2003-2004 trucks. The engine-mounted pump feeds the CP3 about 10 psi, and when it fails the truck simply stops running. Replace the pump and confirm pressure with a gauge before you go back to towing.

Should I use the dealer's in-tank conversion kit?

It's the only transfer pump the dealer network still sells for these trucks, but it isn't your only option. An OEM-style external pump keeps the factory location, so a roadside swap stays possible. Once a truck has the in-tank kit, it needs 2005-style fuel parts from then on.

Is the stock lift pump enough if I've added power?

TDR found the stock pump may not be adequate for much more than 60-70 hp over stock. If your truck runs compliant upgrades past that, watch fuel pressure with a gauge and plan on a frame-mounted pump and filter system with 2-3 micron filtration.

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.