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fuel return or returnless


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Hey everyone running megasquirt setup and we r now dealing with the fuel system..as far as fuel return anyone here ever run a dead end system (returnless)?

On my car I used the stock (metal) return line as the feed line and the plastic line as the return. Works great.

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Don't you need a PWM pump? Can MS2 control that?

Personally I ran 2 new lines under the car along the sill.

'69 2002

'59 MGA

'67 Chevy C20

“Suppose you were an idiot and suppose you were a member of Congress. But I repeat myself.” - Mark Twain

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I know you already know I'm not a fan.. My biggest reason is the fuel pressure regulator uses engine vacuum to deliver a higher PSI of fuel with heavy engine load. The miata guys have a ton to say about it. The stock miata in 1999 and 2000 was returnless. Mazda went away from this system after only 2 years. All the miata guys pull this off. They tend to take it to the next level with dual feel fuel rails. Joe Perez on the Miata Turbo forum did a test with this using a graduated cylinder to measure fuel and found it was identical with dual and single feed fuel rails. To be clear, that's 2 feed lines and 1 return line.

With returnless systems there are 2 types, mechanical and electrical. The mechanical pressure regulators have been used for years. The electrical ones use PWM to reduce the fuel pump and slow down the pressure. Of course this means you need a fuel pressure sensor and something to control it. The MS3 has extra pwm ports, but the software hasn't been written to include that function.

The reason some OEM's do this is clear. It's cheaper for them. In the aftermarket, it's not cheaper. It's more expensive. I've only found one company that does the pump, sensor and controller. http://www.retrotekspeed.com/products/fuel-system-components/

Notice that they say not to use it on the high horsepower injection systems.

I wrote up my fuel line adventure today:


1968 BMW 1600 US VIN 1560713

manufactured on October 2nd, 1967


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