Walbro 255 vs 350 vs 450 vs 525: Which Walbro Fuel Pump Do You Need?

Walk into any fuel pump thread and somebody will tell you to "just get a Walbro." That advice is about as useful as "just get a Ford." There are more than a dozen Walbro performance pumps, the number on the box is measured at a pressure most modern cars never run, and half the lineup is not rated for E85 at all. Pick the wrong one and you either waste money or, worse, run a lean engine with a pump that looked big enough on paper.

This guide settles which Walbro fuel pump fits your build. It covers the whole family: the classic Walbro 255, the newer 350, the gasoline only 400, the E85 rated 450, the 525 Hellcat pump, the 535, the brushless BKS pumps and the in-line pumps that mount outside the tank. We are an authorized dealer for Walbro and sell every pump in this article as a bare pump, so we have no reason to push you up the ladder if the cheaper pump will do.

Flow, current and pressure numbers come from TI Automotive's own published flow sheets (TI has built Walbro automotive pumps for decades and now puts its name on them). Owner results come from threads on DSMtuners, the SR20 Forum, LS1Tech, TurboFord, Bimmerpost, Audizine and the MKIV Supra forum. Prices are ours.

Genuine Walbro pumps, four steps up the ladder

Sourced through authorized channels, never gray market. In stock pumps ship fast.

Gasoline · 300 to 550 hpWalbro 255, GSS341$72.41View pump →Gasoline · 450 to 650 hpWalbro 350, GSS350$106.43View pump →E85 rated · 550 to 850 hpWalbro 450, F90000274$133.70View pump →E85 rated · 650 to 985 hpWalbro 525 Hellcat, F90000285$164.67View pump →

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The Short Answer

• Gasoline, up to about 400 whp: a Walbro 255 (GSS340, GSS341, GSS342 or GSS343, $72.41 to $80.92). Pick the part number by inlet shape, not flow. They are the same pump.
• Gasoline, more than a 255 but still a 39mm hanger: the Walbro 350 (GSS350, GSS351, GSS352, $106.43). It drops into the same spot as a 255 and flows about 22 percent more at 60 psi.
• Any amount of ethanol past pump gas: skip every gasoline pump and start at the Walbro 450. Buy the F90000274 ($133.70) over the F90000267 if your fuel pressure ever goes above 80 psi.
• Big power on E85 from one pump: the 525 Hellcat pump (F90000285, $164.67) or the 535 (F90000295, $181.60). The 535 flows the most but has no internal check valve.
• Past what one brushed pump can do, or you want it quiet: the brushless BKS pumps, from $518.05, plus a controller.

The Walbro Lineup Side by Side

Walbro performance pumps fall into three groups: 39mm gasoline gear pumps (the 255 and 350), 39/50mm turbine pumps (the 400, 450, 525 and 535) and brushless pumps. Inside each group the main differences are inlet shape, pressure rating and whether the pump is rated for E85. The flow figures below are TI's own ratings at 40 psi and 13.5 volts, and the horsepower ranges are TI's crank horsepower ranges across many engines and fuels, so treat them as a guide rather than a promise.

Below the 255 sit TI's 190 lph pumps, the GSS242 ($82.93) and GSS250 ($90.16). They are stock replacement pumps for older fuel injected cars, not upgrades for a tuned one, so the rest of this guide starts at the 255.

Flow at the Pressure Your Car Actually Runs

The number in a Walbro's nickname is its flow at 40 psi, and almost no modern turbocharged car runs 40 psi. A returnless direct injection low side, a boosted port injection car with a 1:1 regulator, or an LS with a 58 psi base all ask the pump for more pressure, and every pump flows less as pressure rises. This table is TI's own averaged bench data at 13.5 volts, converted from gallons per hour and rounded to the nearest liter.

Three things jump out. First, a genuine 255 actually beats its own name at 40 psi, about 275 lph on TI's ten pump average, and it holds up well to 80 psi. Second, the 87 psi pumps, the 400 and the F90000267, fall off hard past 80 psi: at 100 psi the 400 flows less than a 255. Third, the gap between a 255 and a 450 at a real 60 psi is about 133 lph, roughly 53 percent, which is the whole reason the 450 exists.

Two notes on reading it. TI's first test point for the F90000274 was 38 psi and for the F90000295 it was 42 psi, so those two cells sit a couple of psi off. And TI tests with a solvent on the bench, not real gasoline or E85, so differences under about 5 percent are noise.

Gas or E85: The Rating That Matters Most

Every Walbro is either a GAS pump or a FLEX pump, and that rating decides more of your choice than flow does. TI lists the 255, 350, 400 and both in-line pumps as gasoline pumps. The 450, 525, 535 and the brushless pumps are rated for gasoline, E85 and anything in between. TI's own wording for the 400 is that E85 builds should use the 450 instead.

There are two reasons this matters. Ethanol is harder on pump internals and connectors than gasoline, and TI only validates its FLEX pumps for it. And E85 needs roughly a third more fuel volume than gasoline for the same power, so a pump that is comfortable on 93 octane can be out of breath on E85 even if it survives.

Owners argue about the first point endlessly. On Bimmerpost, N54 owners report running a 255 on E70 for years with no failures, while the same thread notes the 450 is the one actually certified for E85. On DSMtuners, the replies to an owner planning E85 on a 255 were blunt: the 255 is not rated for it, plan to replace it every couple of years, or buy a 525 once. Our view is simple. A pump that survives is not the same as a pump that keeps up, and the owner results in the next sections show the 255 runs out of flow on E85 long before it wears out.

What the Part Numbers Actually Mean

Most Walbro part numbers inside a family describe how the pump connects, not how much it flows, so the right part number is the one that fits your hanger and your fuel.

• GSS340, GSS341, GSS342, GSS343 (the 255): same 39mm pump, four inlets. The GSS340 has a 22mm center inlet, the GSS341 an 11mm inlet set 180 degrees from the outlet, the GSS342 an 11mm inlet in line with the outlet, and the GSS343 a 19mm inlet. Match the old pump or your platform install kit. The "G3" on current pumps is TI's revised third generation build.
• F20000311, F20000312, F20000313: TI's versions of the GSS340, 341 and 342 with a higher pressure relief, for cars that run more fuel pressure than a standard 255 is set up for. Worth knowing if a forum post calls for one.
• GSS350, GSS351, GSS352 (the 350): the same three inlet options as the 340, 341 and 342, in a pump that flows about 22 percent more at 60 psi. Same 39mm straight wall body, so it fits a hanger built for a 255.
• F90000262 (the 400): TI's first 39/50mm turbine pump, gasoline only, 87 psi maximum. The lower section is 50mm wide, so it may not fit a hanger built for a 39mm 255.
• F90000267 and F90000274 (the 450): same flow to 80 psi and both FLEX rated. The 274 has a higher pressure relief, 112 psi against 87, and keeps flowing 294 lph at 100 psi where the 267 is down to 206. The old forum story that one is the "gas" 450 and the other the "E85" 450 is wrong.
• F90000285 and F90000295 (the 525 and 535): TI's highest flowing brushed pumps. The 285 has an internal check valve. The 295 does not, which matters the moment you run two pumps.
• BKS1001, BKS1002, BKS1003 (brushless): the 1001 is the pump with TI's matched controller, the 1002 is the pump with filter and harness but no controller, and the 1003 is the bare pump with instructions.

One more naming trap: "Walbro" and "TI Automotive" are the same pumps. TI built Walbro automotive pumps for decades and now stamps its own name on them, so a TI box is not a different or lesser product.

In-Tank or In-Line?

An in-tank pump sits submerged in fuel inside the factory hanger, and an in-line pump mounts outside the tank in the fuel line. For most builds in-tank is the better answer. The fuel cools and quiets the pump, and the factory hanger, sender and pickup stay in place.

The in-line GSL392 and GSL396 earn their place on cars where the tank pump is hard to reach, on carbureted or older EFI conversions, and as a pusher pump after a lift pump or surge tank. They are louder, because nothing surrounds them, and the GSL392 carries a 50 psi maximum, so it is not a pump for a high pressure return style system. The GSL396 is the upgrade: about 298 lph at 60 psi, a 112 psi rating and an internal check valve. Both are gasoline only.

If you are adding a second pump to an existing system rather than replacing one, see our guide to wiring a secondary fuel pump for the relay and trigger side.

Brushless: Is the BKS Worth It?

The brushless pump is worth it in two cases: when one brushed pump is not enough and you do not want two, and when you want a quiet, cool running pump that slows down at cruise. TI rates the BKS pumps at 550 lph at 40 psi, gasoline or flex fuel, and 1,000 plus horsepower.

The efficiency is real. TI's own table for the BKS1001 shows 513 lph at 58 psi with the controller drawing about 8.8 amps and the pump about 7.7. Compare that with the 535 pulling almost 20 amps for 444 lph at 60 psi. Lower current means less heat in the tank and less strain on old wiring.

The catch is the controller. A brushless pump cannot be wired straight to 12 volts like a 255. The BKS1001 ($1,143.27) includes TI's controller, which can run at full speed, at a reduced fixed speed when its command wire is grounded, or follow a PWM signal from your ECU. The BKS1002 ($518.05) is the pump with filter and harness for builds that already have a brushless controller. Price both sides before you decide, because two 450s on a relay can cost less than one brushless setup.

Current Draw and Your Wiring

Every step up the Walbro ladder pulls more current, and factory pump wiring was sized for the factory pump. At 60 psi on TI's bench, a 255 draws about 9.4 amps, a 350 about 13.8, a 450 about 17 and a 525 about 20.6. That is double the 255's load by the time you reach a 450.

The cost of ignoring this is voltage drop, and voltage drop is lost flow. TI's own sheets show the same pump flowing noticeably less at 12 volts than at 13.5. On Audizine, owners swapping in a 450 recommend running a relay fed from the battery and using the factory pump wire only as the trigger, and one member said he has seen melted tank lids from pumps that drew more than the factory wiring could carry. On TurboFord, the reply to an SVO owner going lean on E85 with a 255 pointed straight at voltage drop in the factory harness.

One myth to drop: an LS1Tech reply claimed a 450 draws less current than a 255. TI's data says the opposite, about 17 amps against about 9 at 60 psi. Plan the wiring for the bigger number. And if you want a thorough way to confirm the pump is keeping up after the swap, our wideband AFR gauge guide covers what to watch.

What Owners Actually Say

Owners who matched the pump to their fuel and gave it clean power report years of trouble free running. The complaints trace to the wrong fuel rating, tired wiring, counterfeit pumps or noise. These are paraphrased from the threads, with the forum named and no usernames.

The 255 that hit its limit on E85. On the SR20 Forum, a tuner described an S13 making 414 whp on a Walbro 255 high pressure pump with E85, 3 bar base fuel pressure and 22 psi of boost on 750cc injectors. The pump was at its limit: the mixture drifted close to stoichiometric under boost, and when the turbo came off the exhaust wheel was bleached white from running lean for long stretches. His conclusion was that about 400 whp on E85 is the safe ceiling for a 255.

• Same pump, different answer, TurboFord: an SVO owner with a 255 and 85 lb injectors went lean at high rpm on E85. One reply blamed voltage drop in the factory wiring and recommended a heavy ground straight to the pump. Another argued a single 255 can feed about 475 whp on E85, but only with injectors of at least 1,000cc, rail pressure held near 70 psi and a richish high 11s air fuel ratio. Read the two together and the lesson is that the 255 is right at its edge in that range.
• LT1 stroker on E85, LS1Tech: a 385ci LT1 owner on E85 with a single 255 asked whether he needed more pump. The answer was that E85's extra fuel demand caps a 255 at roughly 450 crank horsepower, and to watch fuel pressure and AFR for the almost linear leaning that shows a pump running out. The suggested upgrade was a 450 with a hardwire kit.
• One 450 or two 255s, DSMtuners: an owner targeting 600 hp on E85 asked whether to run dual 255s or a single 450. The reply favored the single 450, one less pump to fail and a simpler install.
• The 255 that is still loud, LS1Tech: an owner on his third Walbro 255, in an LS swapped 1960 Oldsmobile with a new tank and 10 gauge wiring, still found it loud, while other members said theirs are barely audible at idle. On ClubLexus, a Lexus owner muffled his with an old moving blanket over the tank. The gerotor 255 and 350 whine more than the turbine style 450 and up.
• Which 450, Audizine: an Audi owner confused by the F90000267 and F90000274 was told the 274 is the updated version with the higher pressure relief. The thread then turned to wiring, with the hardwire advice above.

Mistakes We See

• Shopping by the number on the box. A "450" is about a 386 lph pump at 60 psi, and a "255" is about a 253 lph pump. Size the pump from the column that matches your fuel pressure.
• Running a gasoline pump on E85. The 255, 350 and 400 are GAS rated. If ethanol content ever goes past pump gas blends, start at the 450.
• Buying the wrong inlet. A GSS340 will not drop into a hanger built for a GSS342. Check the inlet against your old pump or your platform install kit before ordering.
• Choosing an 87 psi pump for a high pressure system. The F90000262 and F90000267 fall off sharply past 80 psi. A boosted car with a rising rate regulator often lives above that, and the F90000274 or 525 is the safer choice.
• Using a 535 as the second pump with no check valve. Without one, the other pump pushes fuel back through it, and you get long cranks and stumbles. Use a 525 as pump two or add an inline check valve rated for E85.
• Buying a counterfeit. Fake 255s are common enough that the MKIV Supra forum keeps a spotting guide: genuine pumps have a lightly dappled case, a crisp stamping, a straight inlet, a tapered outlet and weigh about 366 grams. In one published bench test by Strike Engine, a fake 255 drew about 13 amps at low load against about 6 for the genuine pump, and about 15 amps once pressure rose, right at the limit of a 15 amp fuse. Buy from an authorized dealer.
• Skipping the filter and harness. A new pump with an old sock or a melted connector fails early. Use the install kit made for the pump.

Who Should Skip a Fuel Pump Upgrade

If your car has an intake, an exhaust and a mild tune on pump gas, and your logs show fuel pressure holding at target, the factory pump is doing its job and a Walbro is money better spent elsewhere. Upgrade when the logs show pressure sagging under load, when your tuner asks for more fuel, or when you switch to an ethanol blend.

Skip the bigger pumps too if your power goal does not need them. A 525 on a 350 whp gasoline car only adds current draw and heat. And skip the brushless kit unless you either need its flow or truly value the quiet, because the controller adds cost and complexity.

If It Were Our Car

Gasoline, up to about 400 whp: a Walbro 255 in the inlet style your hanger needs, with its install kit. It is the cheapest pump here and still the best value in the lineup. The GSS341 and GSS340 are the two most common.

Gasoline, 400 to 500 whp, 39mm hanger: the Walbro 350 in the matching inlet. It gives you most of the reason people jump to a 450 without changing the hanger.

Any ethanol, or gasoline past 500 whp: the Walbro 450 F90000274. Same price range as the 400, FLEX rated, and it keeps flowing past 80 psi. We would not buy a 400 or an F90000267 new unless the car is gasoline only and the system runs below 80 psi.

E85 past what a 450 supports, single pump: the 525 Hellcat pump. It has the check valve the 535 lacks, which keeps a second pump an easy addition later. Pick the 535 only when you need its extra 10 percent at 60 to 80 psi and you will run it alone.

Dual pumps or 1,000 hp class: two 450s or two 525s on a relay, or a brushless BKS with its controller. The two pump route is cheaper; the brushless route is quieter and kinder to the wiring.

BMW owners comparing the Walbro 450 and 535 against the DeatschWerks DW400 for a 39mm bracket will find that head to head in our Walbro 450 vs 535 vs DW400 guide.

What You Need Besides the Pump

Most Walbro performance pumps ship as a bare pump, and a good install needs a filter sock, a harness and sometimes a hose or platform bracket. TI makes a kit for each case.

• Flex fuel 39mm and 39/50mm pumps: the 400-1168 flex fuel install kit ($52.95) with filter, harness and fuel line, made for the F90000267, F90000274 and F90000285.
• Gasoline 39mm and 39/50mm pumps: the 400-1162 gasoline kit ($52.78) with filter and harness, and the 400-1136 kit ($41.82) made for the F90000262.
• Platform kits: TI makes direct fit kits for the 255 in dozens of cars, from the Fox body and SN95 Mustang to the WRX, Evo, Civic, Integra, S2000, Miata and MKIV Supra. Match the kit number to your car before you order.
• Wiring: a relay fed from the battery with a 10 gauge supply for anything 450 and up, using the factory pump wire as the trigger.

We are an authorized dealer for every brand we carry, and in stock Walbro pumps ship fast. Please read our refund policy before ordering and confirm the inlet, body size and fuel rating first, because a pump that has been in fuel cannot come back.

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The Bottom Line

The number on a Walbro tells you its flow at 40 psi, not at the pressure your car runs, and it says nothing about E85. On gasoline, the 255 is still the best value up to about 400 whp and the 350 stretches the same 39mm hanger further. The moment ethanol enters the picture, start at the FLEX rated 450, and buy the F90000274 over the F90000267 if your pressure ever goes past 80 psi. Step to the 525 or 535 for big single pump E85 builds, and to brushless when you need even more or want it quiet. Whatever you buy, buy it genuine, give it the right install kit and feed it with real wiring, because that is where most Walbro complaints actually come from.

Frequently Asked Questions

What is the difference between a Walbro 255 and a Walbro 450?

The 255 is a 39mm gasoline only gear pump that flows about 253 lph at 60 psi on TI's bench. The 450 is a 39/50mm turbine pump rated for E85 that flows about 381 to 386 lph at 60 psi, roughly 50 percent more, while drawing about 17 amps against about 9.

Can a Walbro 255 run E85?

TI rates the 255 (GSS340 to GSS343) for gasoline only. Some owners run one on ethanol blends for years, but E85 needs about a third more fuel, and owners report the 255 running out of flow around 400 whp on E85. For any ethanol build, TI's FLEX rated 450 and up are the right pumps.

What is the difference between GSS340, GSS341 and GSS342?

They are the same 255 lph pump with different inlets. The GSS340 has a 22mm center inlet, the GSS341 has an 11mm inlet set 180 degrees from the outlet, and the GSS342 has an 11mm inlet in line with the outlet. Pick the one that matches your hanger or install kit.

Is the Walbro 400 (F90000262) E85 compatible?

No. TI lists the F90000262 as a gasoline pump and points E85 builds to the 450. It also has an 87 psi maximum, so it flows only about 155 lph at 100 psi on TI's bench.

Which Walbro 450 should I buy, F90000267 or F90000274?

Both are FLEX rated and flow the same to 80 psi. The F90000274 has a 112 psi maximum against 87 psi for the F90000267 and still flows about 294 lph at 100 psi, where the 267 drops to about 206. If your fuel pressure ever goes above 80 psi, buy the 274.

How much horsepower does a Walbro 525 support?

TI rates both the 525 (F90000285) and the 535 (F90000295) for 650 to 985 crank horsepower depending on fuel and pressure. On TI's bench the 525 flows about 404 lph at 60 psi and the 535 about 444 lph, and both are rated for E85.

Does a brushless Walbro need a controller?

Yes. A brushless BKS pump cannot be wired straight to 12 volts. The BKS1001 kit includes TI's controller, which can run full speed, a reduced fixed speed or follow a PWM signal. The BKS1002 is the pump with filter and harness for builds that already have a controller.

How can I tell if my Walbro pump is fake?

Genuine pumps have a lightly dappled case, a crisp stamping, a straight inlet, a tapered outlet and a 255 weighs about 366 grams. Counterfeits often draw far more current; one bench test found a fake 255 pulling about 13 amps at low load against about 6 for a genuine pump. Buying from an authorized dealer is the only reliable protection.