Mitsubishi 3000GT & Dodge Stealth Fuel Pump Guide: Stock vs. Upgraded, Turbo vs. Non-Turbo

May 16, 2026

The 3000GT / Stealth fuel pump is overdue for replacement on most surviving cars

If you own a 1991–1999 Mitsubishi 3000GT, GTO, or Dodge Stealth, your fuel pump assembly is somewhere between 25 and 35 years old. That is well beyond the design life of any in-tank fuel pump from that era, and it is the reason that 'hard hot starts', 'losing fuel pressure at the top of third gear', and 'whine that gets louder with the radio off' are some of the most common complaints in the 3SI community.

This guide covers everything you need to decide when to replace the pump, which version you have, what flow rate is right for your application, and how to do the job once you have the part.

How to know if your fuel pump is dying

These are the signs that point specifically to fuel pump wear rather than other fuel-system issues like the filter, the pressure regulator, or the FPR resistor:

Audible whine from the rear of the car, especially with the radio off and at idle
Hard hot starts after a fuel stop on a long drive
Fuel pressure dropping under sustained load, especially in higher gears
Intermittent stumbling under boost (Turbo cars)
Slow cranking before the engine catches in the morning
Random surging at part throttle

If you have several of these symptoms together, especially on a car with unknown service history, the pump is almost certainly the cause.

Turbo vs. Non-Turbo: two different pumps, two different part numbers

This is the single most important thing to get right when ordering. The 3000GT and Stealth came with two distinct fuel pump assemblies depending on whether the car was naturally aspirated or twin-turbo:

Non-Turbo (3000GT base / SL, Stealth base / ES / R/T NA): OEM part numbers MB678806 / MB698857. Stock flow rate: 100 LPH.
Turbo (3000GT VR4, GTO Twin Turbo, Stealth R/T Turbo): OEM part numbers MB678807 / MB698858. Stock flow rate: 160 LPH.

The assemblies look superficially similar but have different motors, different internal flow paths, and different harness configurations. Fitting a non-turbo pump to a turbo car is a recipe for fuel starvation under boost. Fitting a turbo pump to a non-turbo car will work but is significant overkill.

How much flow do you actually need?

There's a tendency in the 3SI community to spec the biggest pump available — usually a Walbro 255 LPH — regardless of the car's actual power level. This is not always the right call.

For stock or lightly modified non-turbo cars

The original 100 LPH unit is genuinely undersized after 30 years of wear, even for stock power. A modern replacement that flows 130 LPH at 43 PSI gives you comfortable headroom for fresh fuel, ethanol-blended pump gas, and clean injectors, without overwhelming the OEM pressure regulator or relay. This is exactly the spec of our Mitsubishi 3000GT / Stealth Non-Turbo Fuel Pump Assembly (replaces MB678806 / MB698857).

For stock-to-mid-power Turbo cars (up to about 400 whp)

The original 160 LPH unit is the right size category, but a worn one is leaving fuel pressure on the table at exactly the moment you can't afford it. A modern 185 LPH replacement gives you a meaningful upgrade — about 15 percent more flow at 43 PSI / 13.5 V under boost — without changing the fuel-system architecture. The amperage draw stays similar to stock, which is critical: a high-current aftermarket pump can burn out the OEM fueling-circuit relay, leaving you stranded. Our Mitsubishi 3000GT VR4 / Stealth R/T Turbo Fuel Pump Assembly (replaces MB678807 / MB698858) is engineered for exactly this use case.

For seriously modified Turbo cars (500+ whp, big single, E85)

At this level you are out of the OEM-style pump territory and should be looking at a 255 LPH or larger high-pressure pump on a dedicated hardwired circuit. That's a different conversation and outside the scope of a drop-in OEM-style replacement.

The Walbro myth: Forum lore often suggests that a Walbro 255 is the only sensible upgrade for any 3000GT. For genuinely high-power builds, it is excellent. For an otherwise stock VR4 driven on the weekend, it is overkill — and the higher amperage draw stresses your already-aged relay. Match the pump to the build.

Why a complete assembly beats a 'pump only' swap

It's possible to drop just the pump motor into the original assembly. We don't recommend it for cars that haven't had this assembly out in 20+ years, for three reasons:

The original wiring inside the assembly has cooked. PTFE wiring in a modern replacement is fuel- and heat-resistant in a way 30-year-old wiring is not.
The rubber hoses inside the assembly are at the end of their service life and will start cracking shortly after disturbance.
The top rubber seal that sits between the cap and the tank flange almost always tears on removal.

Replacing the entire assembly — with new wiring, new hoses, new seal, and a freshly-engineered motor — is one job, done once. Replacing just the pump motor is a job you'll be doing again within a year or two.

Installation: the Mitsubishi technical bulletin warning

This is the single most important thing every 3000GT / Stealth owner needs to know before attempting this job, and it is missed by most general-purpose YouTube tutorials. We're going to be explicit:

CRITICAL: The OEM rubber fuel line connected to the pump assembly's hard line CANNOT be removed by twisting from the top. Both connector sockets are fixed and do not rotate. If you try to force it from above, you will damage the hard line and the assembly. The line must be disconnected from underneath the vehicle, where the hard-line connector can rotate freely.

Once the line is loose from underneath, the rubber section can be detached at the pump side. This single fact saves more 3000GT/Stealth fuel pump jobs than any other tip.

Other practical notes:

Run the tank low — under a quarter — before starting
Apply penetrating oil generously to the assembly retaining nuts at least an hour before removal. They will be rusty. Plan for it.
Disconnect the battery before working on the fuel system
Relieve fuel system pressure at the rail before opening any fuel line
The pump cover is accessed by removing trim in the rear hatch area — service-manual specific to your year
Replace the top rubber seal at the same time as the pump. Don't reuse the old one — it will leak.

How long should the new pump last?

Both our non-turbo and turbo pump assemblies use carbon-commutator motors engineered from the ground up, PTFE wiring throughout, and fuel-resistant rubber components. Each design was road-tested over thousands of miles before release. With a clean fuel filter, fuel of normal quality, and the pump never run dry, you should expect a service life comparable to the original Mitsubishi pump in 1991 — but starting from zero hours rather than 30 years.

Frequently asked questions

Will the non-turbo pump fit a VR4?

No. The flow rate is insufficient and the harness configuration differs. Always match the pump to the car's original configuration. If you're unsure which you have, check the OEM number on the existing assembly.

Does the new pump require any tuning changes?

No. Both pumps maintain the original fuel-system pressure characteristics — they just supply more volume at the same pressure. Your stock ECU, FPR, and injectors will operate normally.

Is this quiet, or will it whine like an aftermarket pump?

The Turbo pump motor was specifically designed for quiet operation despite the higher flow rate. This is a major difference from a Walbro 255, which is notably louder in normal operation.

Will the pump burn out my relay?

No. Amperage draw is engineered to be similar to the stock unit, specifically to protect the fueling-circuit relay. This is a deliberate design choice that separates an OEM-style upgrade from a generic high-flow drop-in.

How long does shipping take?

We ship from the EU with tracked delivery worldwide. Europe typically arrives in 3–7 business days; the US, UK, Canada, Australia and Asia in 7–14 business days depending on customs.