The gas 6.4L (and earlier 5.7L) Power Wagon uses a returnless EFI system with the pump, pressure regulator, and filter all built into a single in-tank module — there is no serviceable inline fuel filter to swap. When you get long cranks, hard hot-starts, or a no-start with a dead fuel-pump prime, you measure rail pressure first and replace the whole module if it is low. Budget around $280 for a quality module and the better part of an afternoon, because the tank has to come down.
A lot of owners go looking for a "fuel filter" on this truck and never find one. On the gas Hemi the filter is the in-tank strainer/sock that comes as part of the pump module — Ram designed it as a lifetime, non-serviceable assembly. That changes the service strategy: you do not do a routine filter swap, you diagnose pressure and replace the module when it fails. The good news is the system is reliable; the catch is that the job means dropping or substantially lowering a long, often-full tank under a heavy frame.
Symptoms that point at the pump module are extended cranking before start, hard restarts when hot, stumbling under load, or a no-start where you cannot hear the two-second pump prime when you cycle the key to RUN. Before buying parts, put a gauge on the fuel rail's Schrader test port (or splice an in-line gauge) and key on: a healthy gas Hemi should build to spec (roughly 58 psi class, verify against the service manual) and hold pressure after shutoff. Low or slowly-bleeding pressure with the engine off can be the pump, a leaking regulator inside the module, or a failing check valve — all of which live in the same module, so the fix is the same. Pull codes too; a P0order in the P0230 family supports a pump-circuit fault.
Run the tank as low as you can before you start — a full tank is heavy and dangerous to support. Relieve fuel pressure (pull the pump relay and crank briefly, or follow the manual's procedure), then disconnect the battery. Raise the truck on rated stands. Support the tank on a transmission jack, remove the straps and the filler/vent and electrical connections, and lower it enough to reach the top. Rotate the lock ring off with a brass drift or lock-ring tool, lift the old module out carefully (the float arm bends), set the new seal, and drop the new module in clocked the same way. Reconnect, raise the tank, and cycle the key several times to prime before cranking.
Re-check rail pressure with the gauge, then look for weeping at the lock ring and lines under pressure before lowering the truck. Clear any stored codes. If the original failure was contamination (a tank of bad fuel), inspect the strainer condition and consider a tank clean-out so you are not feeding debris into the new module.
The module itself is the whole cost story. A quality complete assembly — Mopar OE, Delphi, or Spectra — runs about $220-320; the lock-ring seal is another $15-20, and a fuel-pressure gauge you'll reuse is $40-50. Doing it yourself, call it $280 in parts and an afternoon. A shop charges $500-700 for the same job because the labor is the tank drop, not the swap. Skip the cheapest no-name modules — a $90 pump that fails in a year means dropping the tank twice, which erases every dollar saved. If the truck is high-mileage, doing the pump also gets the aging strainer sock replaced as part of the module, which is a quiet reliability win.
Most Power Wagon pump failures are either high-mileage wear or contamination, and the second is partly in your control. Don't run the tank down to fumes as a habit — the fuel in the tank cools and lubricates the in-tank pump, and chronic near-empty running shortens its life. On a truck that fords water, make sure the tank vent and filler are sealed and routed high so a deep crossing doesn't pull water past a bad seal into the tank; if you find water or debris, plan a tank clean-out before it reaches the new module. Pair a suspected fuel issue with a code scan from the OBD-II diagnostic guide so you separate a pump-circuit fault from a plugged strainer, and keep the whole fuel-and-ignition side honest with the fluid-service schedule.
| Part | Vendor | Est. price |
|---|---|---|
| Complete in-tank fuel pump module (pump + sender + strainer) | Mopar / Delphi / Spectra | ~$280 |
| Tank lock-ring seal / gasket | Mopar | ~$18 |
| Fuel-pressure test gauge kit | OTC / Mityvac | ~$45 |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.
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