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Diesel lift pump fuel system
October 20, 2026 Travis Walker

Diesel Lift Pump Guide: FASS vs AirDog vs Irate Diesel for Every Powerstroke, Cummins and Duramax

The CP4, the VP44, the CP3, the HEUI injectors on a 7.3 or 6.0: every diesel fuel system has one thing in common. It needs a steady, clean supply of fuel to survive. Starve it, and parts wear out or come apart. A lift pump is how you make sure that never happens.

This guide covers every truck we sell lift pumps for: 7.3, 6.0, 6.4 and 6.7 Powerstroke, 12 valve, 24 valve and common rail Cummins, and every Duramax from the LB7 to the L5P. Find your truck below, then add the parts that finish the job: a fuel bowl delete, a regulated return or a sump.

What a Lift Pump Does

A lift pump pulls fuel from the tank and feeds the injection system at steady pressure. FASS, AirDog and Irate Diesel systems do more than the factory pump:

  • Steady supply pressure so the injection pump or injectors never see a vacuum
  • Air and vapor removal on FASS and AirDog, which helps the pump, the injectors and fuel economy
  • Better filtration and water separation ahead of the expensive parts
  • Headroom for more fuel when you add injectors, a bigger pump or a tune

Do You Need One?

  • 7.3 and 6.0 Powerstroke: yes if you run bigger injectors or a tune. Low fuel pressure is hard on HEUI injectors, and a lift pump with a regulated return holds pressure steady.
  • 5.9 24 valve Cummins: yes. A weak lift pump is the biggest killer of the VP44.
  • 6.7 Powerstroke and LML Duramax with a CP4.2: yes. Fuel starvation is one of the main ways a CP4 fails. Read our 6.7 Powerstroke pump guide.
  • Any tuned truck, or one with bigger injectors or a stroker pump: yes.
  • Stock truck that tows heavy or runs high miles: strongly recommended.

FASS vs AirDog vs Irate Diesel

All three are proven systems we sell and install. FASS and AirDog cover almost every diesel truck. Irate Diesel builds complete fuel systems for the 7.3 and 6.0 Powerstroke.

FASS AirDog Irate Diesel
Trucks covered Powerstroke, Cummins, Duramax Powerstroke, Cummins, Duramax 7.3 and 6.0 Powerstroke
Flow options 100 to 290 GPH, plus a 360 GPH competition pump 100 to 220 GPH Bosch electric pump on the complete systems, Fuelab pump on the basic competition system
Air and vapor removal Yes Yes, returns air and vapor to the tank No, built around a regulated return
Regulated return Add separately Add separately Included on the complete systems
Product lines Titanium Signature (frame mount), No Drop Titanium, Drop In Series (in tank) 4G (FP-100, FP-150) and II-5G (DF-100, DF-165, DF-220) 7.3 OBS electric system, 7.3 Super Duty standard system, 6.0 complete Bosch system, basic competition system, regulated return kit
Warranty See listing See listing See listing

Honest take: any of them is a huge step up from stock. Pick the kit that fits your truck and your power goal, and add the supporting parts below.

How to Size a Lift Pump

Build Lift pump size
Stock to mild tune 100 to 165 GPH
Bigger injectors, stroker pump or towing heavy with a tune 165 to 220 GPH
Big injectors, dual pumps, competition 220 to 290 GPH, or the FASS COMP 360

Bigger is not always better on a stock truck. Match the pump to where the truck is going, and leave a little room to grow.

Lift Pumps by Truck

Every kit below is truck specific. Links go straight to the listing for your year.

7.3 Powerstroke OBS (1994 to 1997)

The OBS 7.3 runs a mechanical lift pump off the cam. Irate Diesel replaces it with an electric pump and a regulated return, which is the setup most built OBS trucks run.

7.3 Powerstroke Super Duty (1999 to 2003)

Excursion owners: FASS makes 2000 to 2005 Excursion kits, see the Excursion links in the 6.0 section.

6.0 Powerstroke (2003 to 2007)

The 6.0 is hard on injectors when fuel pressure drops. A lift pump plus a regulated return keeps pressure steady at the rail, and the fuel bowl delete removes the leak prone factory housing once the lift pump is doing the filtering.

6.4 Powerstroke (2008 to 2010)

6.7 Powerstroke (2011 to 2016)

This truck has a CP4.2. Fuel starvation is one of the main ways a CP4 fails, so a lift pump is the cheapest insurance you can buy. Read our 6.7 Powerstroke pump guide and see every CP4 disaster prevention kit.

6.7 Powerstroke (2017 and newer)

12 valve Cummins (1989 to 1998)

24 valve Cummins (1998.5 to 2002) and 2003 to 2004 common rail

A weak lift pump is the number one killer of the VP44. Read VP44 failure signs and see every VP44 injection pump we carry.

5.9 and 6.7 Cummins (2004.5 to 2018)

6.7 Cummins (2019 and newer)

AirDog does not list a kit for 2019 and newer Rams in our catalog. Call us and we will check current fitment.

Duramax LB7, LLY, LBZ and LMM (2001 to 2010)

LML Duramax (2011 to 2016)

The LML runs a CP4.2 like the 6.7 Powerstroke, so the same rule applies: keep it fed and it lives longer.

L5P Duramax (2017 and newer)

AirDog does not list an L5P kit in our catalog. Call us and we will check current fitment.

Do not see your truck? FASS makes a universal 100 GPH and 140 GPH system. Or send us your VIN and we will match one.

Finish the Job: Fuel Bowl Deletes, Regulated Returns and Sumps

Fuel bowl and filter deletes

Once a FASS or AirDog is filtering the fuel on the frame, the factory filter housing on the engine is just another leak point and restriction. A delete or relocation kit takes it out of the picture. Only delete it when your new system has its own filtration.

Regulated returns

A regulated return puts an adjustable regulator and a dedicated return line on the fuel system, so pressure at the injectors stays steady instead of dropping under load. It matters most on the HEUI 7.3 and 6.0, where injectors depend on good fuel pressure, and on any truck with bigger injectors.

Sumps and pickups

The factory pickup can suck air on hills, hard turns and a low tank. A sump puts the pickup at the very bottom of the tank so your lift pump gets solid fuel down to the last few gallons. It is the most overlooked part of a fuel system upgrade.

Install Tips

  • Prime the system before you crank the engine, every time you change filters.
  • Add a gauge or warning light so you know if pressure drops. AirDog sells a low pressure indicator light kit, and Irate Diesel sells a 0 to 120 psi liquid filled fuel pressure gauge.
  • Run a sump on any build over 165 GPH so the pump is never pulling air at low fuel.
  • Change filters on schedule. A clogged filter undoes everything the pump is doing for you.

Shop Fuel System Parts

More reading: S&S fuel system planner • Signs your injectors are failing

FAQ

Do I need a lift pump on a stock diesel truck?

On trucks with a CP4 or VP44 injection pump, a lift pump is strongly recommended even when stock, because fuel starvation is one of the main causes of pump failure. On a 7.3 or 6.0 it matters most once you add injectors or a tune.

FASS or AirDog: which is better?

Both remove air and vapor, add filtration and come in truck specific kits for Powerstroke, Cummins and Duramax. AirDog goes up to 220 GPH. FASS goes up to 290 GPH and offers No Drop and in tank Drop In versions. Pick the kit that fits your truck and your power goals.

What is the best lift pump for a 7.3 Powerstroke?

FASS and AirDog both make 1999 to 2003 kits. Irate Diesel builds complete 7.3 systems with a Bosch electric pump and a regulated return, including an electric conversion for the 1994 to 1997 OBS trucks.

Do I need a regulated return with a lift pump?

On a 7.3 or 6.0, or any truck with bigger injectors, a regulated return keeps fuel pressure steady at the injectors and is worth adding. On a stock common rail truck the lift pump alone covers most of the benefit.

What does a fuel tank sump do?

It moves the fuel pickup to the bottom of the tank so the lift pump keeps getting solid fuel on hills, in hard turns and when the tank is low. It is recommended on any build over 165 GPH.

Does the FASS lift pump for the L5P Duramax need a tune?

FASS lists its 2017 to 2019 L5P Titanium 140 and 220 GPH kits as tune required.

Not sure what fits your truck? Send us your VIN or call 865 640 2097 and we will help you pick the right parts.

Powerhouse Diesel, Knoxville, TN. Diesel repair and performance parts, shipped nationwide. About us • Meet the team • Wholesale

Filed in: AirDog, Buyer Guide, Cummins, Duramax, FASS, Fuel System, Lift Pump, Powerstroke
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