BMW N55 Fuel Pump Upgrades | The Complete OneFastShop LPFP Lineup

If you have started tuning a BMW N55, you have probably already learned that the stock low pressure fuel pump (LPFP) is one of the first things to hold you back. The N55's direct-injection fuel system relies on the in-tank LPFP to feed its high pressure pump, and once you move past a basic tune, add E85, or turn up the boost, the factory pump simply cannot supply enough volume. That is where the OneFastShop N55 LPFP lineup comes in. This guide walks through every stage we offer, what each one supports, and how to choose the right one for your build.

Why the LPFP Is Your First Fueling Bottleneck

On the N55, the low pressure pump in the tank delivers fuel to the engine-driven high pressure pump, which then feeds the injectors. The factory LPFP is sized for a stock car, so as soon as you increase power demand it starts running out of headroom. The result is fuel pressure that drops under load, which shows up as a lean condition at the top of the rev range exactly where you need fueling most.

Upgrading the LPFP restores the volume your engine needs and unlocks the fueling required for higher boost, larger injectors, and ethanol blends. Every pump in our lineup is a complete, E85-compatible drop-in assembly built to directly replace the BMW OEM unit, so you are not piecing together brackets and fittings yourself.

The OneFastShop N55 LPFP Lineup

Our N55 pumps are organized by stage, with each step up adding fuel volume to support a higher power target. Every assembly ships fully built with the pump pre-installed, a complete replacement fuel bucket, top hat and float, filter, fittings, and O-ring.

Stage 2 - Walbro 450 | Up to 575 WHP

The Stage 2 LPFP is built around the proven Walbro 450 (F90000274) pump and supports up to 575 WHP on pump gas or 500 WHP on full E85. It is the ideal starting point for Stage 2 and Stage 2+ tunes, and it installs plug-and-play with no wiring modifications. For most street-driven N55 builds running a tune and maybe a bit of ethanol, this is the pump that gets the job done.

Stage 2.5 - Walbro 535 | Up to 650 WHP

The Stage 2.5 LPFP steps up to the higher-output Walbro 535 (F90000295) pump, supporting up to 650 WHP on pump gas or 550 WHP on full E85. It is the natural choice if you are running higher ethanol content or want extra headroom over the Stage 2 without moving to a dual-pump setup.

Stage 2.5+ - DeatschWerks DW400 | Up to 700 WHP

The Stage 2.5+ LPFP uses the high-output DeatschWerks DW400 pump and supports up to 700 WHP. It is the top single-pump option in the lineup, giving aggressive single-turbo and E85 builds maximum volume while still keeping the simplicity of a plug-and-play install.

Stage 3 - Dual Walbro 450 | Up to 850 WHP

When a single pump is no longer enough, the Stage 3 LPFP brings in dual Walbro 450 pumps to support up to 850 WHP on pump gas or 800 WHP on E85. A boost-referenced pressure switch (Hobbs switch) automatically brings the second pump online when you need it, and the whole assembly arrives fully pre-wired - no splicing or cutting required. It is compatible with Reflex and Pro EFI controllers and suited to upgraded turbo and port-injection builds.

Stage 3.5 - Walbro 450 + 535 | Up to 950 WHP

The flagship Stage 3.5 LPFP pairs a Walbro 450 primary with a Walbro 535 secondary to support up to 950 WHP on pump gas or 875 WHP on E85. Like the Stage 3, it is fully pre-wired with a boost-referenced Hobbs switch for automatic secondary activation. This is the pump for the most serious high-boost, ethanol, and port-injected N55 builds.

N55 LPFP Lineup at a Glance

Which Stage Is Right for You?

The right pump comes down to your power goal and your fuel. A few simple guidelines:

• Stage 2 (Walbro 450): street builds on a tune, mild boost, light ethanol blends up to about 575 WHP.
• Stage 2.5 (Walbro 535): higher ethanol content or extra headroom up to about 650 WHP, still single-pump simplicity.
• Stage 2.5+ (DW400): the maximum single-pump option for aggressive E85 and single-turbo setups up to about 700 WHP.
• Stage 3 (Dual 450): high-boost and port-injection builds that need dual-pump volume up to about 850 WHP.
• Stage 3.5 (450 + 535): the top of the lineup for the highest-output N55 builds up to about 950 WHP.

As a rule of thumb, choose the stage that comfortably exceeds your current target so the pump is not maxed out, and remember that E85 needs roughly 30 percent more fuel volume than pump gas for the same power.

Fitment

The N55 LPFP lineup above is built for F-chassis N55 and N20 applications and is a direct replacement for BMW OEM part #16117243975. That covers cars such as the F22 / F23 M235i, F87 M2, F30 / F31 335i, F34 GT, and F32 / F33 / F36 435i, along with their N20 counterparts.

One important note: early E-chassis N55 cars - the 2011 to 2013 135i and 335i, and the E84 X1 xDrive35i - use a different fuel bucket (OEM #16147163298) and take our E-chassis assemblies instead. If you drive one of those, browse the full fuel pumps collection to find the correct E-chassis pump for your car, or reach out and we will confirm the right fit.

Installation Notes

Every single-pump assembly is plug-and-play with no wiring modifications, soldering, or ECU changes, and ships ready to drop in. The dual-pump Stage 3 and Stage 3.5 kits arrive fully pre-wired with the boost-referenced pressure switch and harnesses configured, so there is still no splicing or cutting required. A fuel pump lock ring removal tool is needed to access the pump in the tank - if you do not already have one, you can add the correct lock ring tool to your order. After installing any upgraded LPFP, have your tuner update the fueling in your map to take advantage of the added volume.

Conclusion

Whether you are chasing a reliable 575 WHP on a daily-driven N55 or building a 950 WHP monster, there is a pump in the OneFastShop lineup matched to your goal. Start with your power target and fuel type, pick the stage that gives you headroom, and confirm fitment for your chassis. Ready to upgrade? Explore the complete N55 fuel pump lineup and give your build the fuel system it deserves.

Frequently Asked Questions

Which N55 fuel pump do I need?

It depends on your power goal and fuel. Stage 2 (Walbro 450) suits street tunes up to about 575 WHP, Stage 2.5 and 2.5+ cover higher single-pump targets up to 650 and 700 WHP, and the dual-pump Stage 3 and 3.5 support 850 and 950 WHP for the most aggressive builds. Pick a stage that exceeds your current target for headroom.

Will these pumps fit my E-chassis 135i or 335i?

The lineup in this guide is for F-chassis N55 and N20 cars (OEM #16117243975). Early E-chassis N55 cars - the 2011 to 2013 135i and 335i and the X1 xDrive35i - use a different bucket (OEM #16147163298) and take our E-chassis assemblies. Check the fuel pumps collection or contact us to confirm the right pump for your chassis.

Are these N55 fuel pumps E85 compatible?

Yes. Every pump in the lineup is E85-compatible and works with pump gas, ethanol blends, and methanol injection, making them suitable for flex-fuel and dedicated ethanol builds.

Is installation plug-and-play?

The single-pump assemblies are fully plug-and-play with no wiring modifications. The dual-pump Stage 3 and 3.5 kits ship pre-wired with the pressure switch and harnesses configured, so no splicing or cutting is needed. A fuel pump lock ring removal tool is required to access the pump in the tank.

Do I need a tune after upgrading my LPFP?

Yes. To take advantage of the added fuel volume and run the boost or ethanol content the pump enables, your tuner should update the fueling in your map after installation.

Do the dual-pump kits need extra wiring?

No. The Stage 3 and Stage 3.5 assemblies arrive fully pre-assembled and pre-wired with a boost-referenced pressure switch (Hobbs switch) that automatically brings the second pump online, plus the required trigger and activation harnesses. No splicing, cutting, or crimping is required.