How To: Ram 6.7L Cummins Change BOTH Fuel Filters
, by iFJF Direct, 10 min reading time
🛒 Parts Used in This Guide 6.7L Cummins Fuel Filter & Water Separator Kit for Ram 2500 $36.00 Shop Now → 68157291AA 68436631AA Fuel Filter Kit for 2019-2020 Ram 6.7L $29.99 Shop Now → 68157291AA Fuel ...
🛒 Parts Used in This Guide
Ram 6.7L Cummins Fuel Filter Replacement — Both Filters, Step by Step
If you own a Ram 2500 or 3500 with the 6.7L Cummins, fuel-filter service is one of the highest-value maintenance jobs you can do yourself. Unlike a gas truck with a single in-line filter, the 6.7 Cummins runs two diesel fuel filters — a chassis-mounted (frame-rail) filter and an engine-bay filter — and both need to come out on the same service. This guide walks through the full job on a 2024 Ram 2500, including the tools, the torques, the drain tricks, and the priming step that keeps your injection pump alive.
Your owner's manual sets the minimum interval, but most Cummins owners change both filters alongside every oil change. The truck's "Fuel Filter Life" indicator makes this easy — when it hits 0% it's time. Clean fuel is non-negotiable on a high-pressure common-rail diesel: abrasive particles and emulsified water are what kill injectors and CP4-style pumps. A $30 filter set is the cheapest insurance you can buy.
Tools & Parts You'll Need
| Item | Notes |
|---|---|
| Two fuel filters (chassis + engine-bay) | Must meet manual spec: 5-micron chassis, 3-micron engine-bay |
| Two replacement O-rings | Different sizes — keep track of which goes where |
| Clean engine oil or petroleum jelly | Lubes the O-rings so they seat without twisting |
| Clear catch container | Lets you see water/contaminants in the drained fuel |
| 28 mm socket + long extension + swivel | 28 mm grips the housing nut tighter than a 1-1/8" |
| Ratchet and/or breaker bar | Breaker bar gives controlled leverage on tight housings |
| 1/4" fuel hose (~24") | Slips onto the rear drain nipple |
| 5/8" hose (~24") | Slips over the factory front drain hose to reach your catch pan |
| #2 Phillips screwdriver or pliers | To crack the bleed screws |
Know Your Two Filters Before You Start
The chassis-mounted filter (the "rear" one in this walkthrough) sits under the truck, just forward of the rear axle on the passenger side. On 2024 trucks it's a cartridge that drops into a reusable housing; older trucks used a spin-on canister style with the water-in-fuel sensor on the bottom. The newer design is nicer — the sensor stays put and you only swap the cartridge. The engine-bay filter (the "front" one) lives low on the driver's side near the brake reservoir and opens from the top; it has a yellow bleed screw on the cap.
Your manual states the requirements plainly: the engine-mounted filter must meet a 3-micron rating and the chassis-mounted filter a 5-micron rating. Buy filters that meet or exceed those numbers — don't guess.
Step 1: Drain & Replace the Chassis (Rear) Filter
Get the housing ready
Slide under from the passenger side, past the exhaust and just above the driveshaft. You'll see the housing and a drain petcock at the bottom. Push your 1/4" hose onto the drain nipple and run it into your clear catch container.
Crack the drain and watch for water
Open the petcock — only crack it, never pull it all the way out, or pressurized fuel will squirt you. Let it drain (about 18-20 oz on this truck). This is your best chance to spot water in the fuel: a clean, water-free sample means your supply has been good. Keep the petcock open a little longer than feels necessary so the housing is fully drained before you drop it.
Break the housing loose
Use the 28 mm socket on a swivel and long extension with a breaker bar. Come in from the driver's side of the driveshaft and push up into the socket while rotating — the housing is tight. Once cracked, finish by hand with the ratchet. A little fuel will weep out, so keep a pig mat or rags handy and don't work directly under it.
Swap cartridge and O-ring
The cartridge snaps onto barbs at the bottom of the housing on a small O-ring — this is the smaller of your two O-rings. Lube the new O-ring, seat the new cartridge (it's directional — rotate until it lines up with the housing tabs), and press the housing back up. Start it by hand, snug with the ratchet, and you're done at the rear.
Step 2: Drain & Replace the Engine-Bay (Front) Filter
Extend the factory drain hose
The factory front drain hose is only about 4" long and sits above the front axle crossmembers — useless for catching fuel. Slide your 5/8" hose over it and route it down into your container. Then crack the yellow bleed screw a quarter-turn with the #2 Phillips; you'll hear it draining with no mess.
Open the top cap
With the swivel on the 28 mm socket, brace your hand up top by the brake reservoir and break the cap loose with the breaker bar, then spin it off by hand. Pull the filter straight up — fuel will drip from it, which is normal since the bleed screw is still open.
Swap and reseal
Remove the stretched old O-ring, lube the new one, and drop the new filter in (it's directional — feel which way it seats). Press it fully down, reinstall the cap, and don't forget to close the yellow bleed screw before you move on.
Step 3: Prime the Fuel System
This step is what separates a clean job from a tow truck. After both filters are open to air, the system must be primed before startup.
- Put the key in, push once to ACC, then push again to RUN. The electric fuel pump will run, push fuel and air through the filters and injection pump, then shut off.
- Repeat the ACC→RUN cycle 3 to 5 times. The return line carries the air back to the tank.
- While you wait, reset the dash: hold Reset on the fuel-filter-life prompt until it shows 100%.
- Start the truck, let it idle, and check both filter locations for leaks.
Why this matters: if air reaches the injection pump you risk pump damage and a hard, air-locked non-start. Priming is not optional.
Pro Tips From the Shop
| Tip | Why it matters |
|---|---|
| Use a 28 mm socket, not 1-1/8" | 28 mm fits the housing nut tighter, so you get the break-loose torque without rounding the nut |
| Always do the rear/chassis filter first | You see the drained fuel and any water in your catch container first — a quick health check on your fuel supply |
| Lube every O-ring with oil or dielectric/Petroleum jelly | Dry O-rings twist and pinch, causing slow seeps you'll have to redo |
| Extend both drain hoses to a clear container | Keeps fuel off you and the floor, and lets you confirm "no water" visually |
Ram 6.7 Cummins Fuel Filter Cross-Reference
| Brand | Part # | Position | Micron | Fits |
|---|---|---|---|---|
| iFJF | 68157291AA | Chassis (frame rail) | 5 | 2010-2020 Ram 2500/3500/4500/5500 6.7L |
| Mopar (OEM) | 68157291AA | Chassis | 5 | 2010-2020 Ram 6.7L Cummins |
| Mopar (updated) | 68436631AA | Chassis | 5 | Later Ram 6.7L applications |
| iFJF (engine-bay) | Verify by year/VIN | Engine bay | 3 | Confirm 3-micron requirement for your model year |
Note: Ram redesigned the fuel-filter layout around the 2021 model year. The 2010-2020 chassis filter (68157291AA) and the engine-bay filter differ from the 2021+ setup — always confirm the correct part by your VIN before ordering.
🛒 iFJF 68157291AA 5-Micron Fuel Filter — Ram 6.7L Cummins (2010-2020)
The iFJF 68157291AA is a direct replacement for the chassis-mounted fuel filter on 2010-2020 Ram 2500/3500/4500/5500 trucks with the 6.7L Cummins. It delivers 3-micron-class absolute filtration with water-separation media, protecting your injectors from abrasive wear and tip erosion. Replaces Mopar 68157291AA and 68436631AA at aftermarket pricing.
If you're already under the truck servicing both filters, keep a fresh iFJF 68157291AA on the shelf so you're never waiting on a filter when the life indicator hits zero.
Shop Now →FAQ
How often should I change the fuel filters on a 6.7 Cummins?
Follow your owner's manual minimum interval and the truck's Fuel Filter Life indicator. Most owners pair the service with every oil change. Filters are cheap and easy — doing them more often than the minimum only helps injector longevity.
Why does the 6.7 Cummins have two fuel filters?
Two-stage filtration: the chassis (frame-rail) filter does the heavy lifting on water and coarse contaminants, while the engine-bay filter provides final fine filtration right before the injection pump. Your manual specs 5-micron for the chassis filter and 3-micron for the engine-bay filter.
What happens if I don't prime the fuel system?
Air trapped in the lines can reach the injection pump, risking pump damage and an air-locked no-start. Cycle the key ACC→RUN 3-5 times so the electric pump purges air back through the return line before you crank the engine.
Can I use a 1-1/8" socket instead of 28 mm?
You can, but 28 mm fits the filter-housing nut tighter and gives you the break-loose torque without rounding the nut. Pair it with a swivel and a breaker bar for the tight under-truck access.
Are 2020-and-older Ram fuel filters the same as 2021+?
No. Ram changed the filter design around the 2021 model year (cartridge vs. older canister style and sensor location). The iFJF 68157291AA fits 2010-2020 trucks; confirm the correct part for 2021+ by VIN before ordering.
Related Articles
- Shop Diesel Fuel Filters — frame-rail, engine-bay, and marine fuel filters for Cummins, Duramax, and Powerstroke.
- Diesel Fuel Filter Collection — full cross-reference of iFJF filters by application.
🛠️ Related Maintenance Parts - Grab While You're Wrenching
Since you're already working on your truck, these maintenance items take minutes to swap while everything's apart:
