How to build a fuel system that our MR2 won’t outgrow

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Update by J.G. Pasterjak to the Toyota MR2 Turbo project car
Dec 6, 2022 | Toyota, MR2, Toyota MR2, Deatschwerks, Wilhelm Raceworks

Since we’re thoroughly disassembling our 1991 Toyota MR2 to clean up the fire damage and prep the car for the installation of our 2GR FE V6, we figured it was a good opportunity to take a look at the fuel system and make some upgrades.

The MR2’s fuel pump is buried deep within the hoagie-shaped fuel tank that sits right in the center of the car, while access is hampered by a lot of cooling and brake plumbing as well as some fiddly fuel hose connections.

We’d never have better access than we would now, so we lined up some hardware from DeatschWerks.

First, what fuel pump to get? Using DeatschWerks’ handy fuel pump calculator, we determined our needs based on our expected power level: Most 2GR FE engines in MR2 applications are putting down 295 to 305 horsepower at the wheels when prepped to our expected initial specs.

Then we built in some safety margin for possible future upgrades. What if we want to try E85? What if we find a Lotus Evora or TRD supercharger for a good deal? Having some headspace would be comforting, particularly since cracking into the fuel tank is a pain once the car is back together.

So we settled on a 340lph DW300C pump along with the 9-1000 install kit, which included a new feed hose and clamps, and a square pickup screen.

The DeatschWerks DW300C pump is physically smaller than the original one, but that’s because the new one is far more efficient. It only draws 16 amps at max capacity (which we’ll likely never use).

While the pump’s 340lph capacity may seem like overkill–and, to some extent, it is, particularly for our initial power levels–we went with additional capacity over a “just enough” approach for a couple reasons.

Even at the highest power levels that we’re initially expecting, the pump’s minimal capacity should produce more than enough flow while drawing fewer than 12 amps of current while doing so.

And even in the most extreme, E85 and force-inducted fantasy scenario that may never even come to pass, that same pump will have plenty of capacity and still draw fewer than 16 amps. This means little stress on wiring, and less work for the alternator and electrical system. In the end, we’re getting the benefits of additional headspace without the hassle of high current requirements.

Working our way down the fuel system, we’ll also be incorporating an adjustable DWR 1000c fuel pressure regulator with -6AN fittings, and a DWFF110 fuel filter with 6 micron filtering and also -6AN fittings.

The filter features a removable, cleanable element that’s secured with a spring. Fuel is supposed to flow from the outside of the element to the inside, so assemble the unit accordingly.

The filter’s 6 micron rating provides peace of mind. The setup’s ease of disassembly means periodic maintenance is also a snap.

You may have also noticed that all of our fuel control devices feature -6AN connections, which is not OEM on either a 1991 MR2 or our late-model Camry engine donor.

To convert the tank outlet and inlet to -6AN fittings, you’ll need to trim off one of the stock flares on the return line. A tubing cutter makes this easy but having the tank out of the car makes it easier. It’s doable with the tank in the car–especially with the engine out–but the best time to make this upgrade is when the tank is on the bench.

We’ll be redoing the fuel (and, eventually, oil) fittings to AN standards to keep things consistent and easy to find should we ever need to service anything. To make the conversion, we needed to replace a couple of stock connections with AN hardware. Luckily, Alex Wilhelm at Wilhelm Raceworks is way ahead of us, and has already come up with a premade solution for both the feed and return sides.

Wilhelm’s kit provides prebuilt hoses and adapters to run from the fuel pressure regulator to the engine, and a return line that connects the regulator to the tank. The kit also includes an adapter for the stock Toyota fuel filter.

This setup can be a great convenience for folks who don’t want to mess with the stock fuel feed between the tank and the filter. Our feed burned up in the fire, though, so we’ll just be adapting AN hose from the tank outlet all the way back to the inlet. This is how you’ll want to roll if your existing fuel feed system is older, cracked, or if you want to run an aftermarket filter. Ours checked a lot of those boxes.

You don’t have to tighten your AN hardware with an AN-specific tool, but using an aluminum wrench on the aluminum fittings will reduce the chance of marring or burrs.

As for installation of the pump, it’s pretty straightforward once you get it removed from the tank. It’s considerably smaller than the Walbro that we removed–thank technology and efficiency improvements for that–but fits nicely in the original slot on the end of the stock pump bracket.

You’ll need to trim the stock rubber “foot” that holds it steady in the bracket to make sure the bleed hole on the bottom of the pump is exposed. This hole helps equalize pressure within the pump and helps it prime quickly and efficiently.

When installing the new pump, make sure this bleed hole is clear. We had to trim a bit of material off the rubber foot that holds the pump to the bracket.

With the pump attached to the bracket and the pickup in place, it can go back in the tank, ready to feed our new V6.

We still have a line to build from the tank to the filter and, of course, we need to install all of this stuff back in the car. But it’s nice knowing our new fuel system is now worry free and has capacity to spare.

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