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At 10:17 PM 5/25/2004 -0400, you wrote:
Mark Steitle <msteitle@mail.utexas.edu> wrote:
> > > >
Bill,
Yes, the regulator is mounted on the firewall and is located between the pumps/filters and fuel rail. Also, there is a fuel return line off the regulator.
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Wouldn't it make more sense to make the regulator the last thing in the circuit? This seems to be typical on just about all automotive EFI installations, and millions of installations can't be wrong. I think the logic here is that regulator failures aren't sudden, and when they fail they bypass more fuel than they should (ie, lowering pressure). In this setup there is no way that you can get an airlock, at least I don't see how one would be possible. Proven systems all seem to have the fuel pumps as close to the tank as possible (inside the tank on most auto installations), then the filter, followed by a direct line to the fuel rail and injectors, then to the regulator, then the return. On the Eagle540 we put the fuel filters between the tanks and pumps, and they are located just aft of the main spar, just inches away from the tanks (the filter outlet screws directly into the pump inlet)... out of the pumps to the selector, on through the flow transducers, then to the rails. The regulator is at the end of the circuit and returns through the (horribly expensive) fuel selector as well to direct the return fuel back to the tank from which we're pumping. Everything has worked extremely well in ground runs, and we are weeks away from first flight. Just my 2c.
<Marv>
Hi Marv,
Yes, that was my original intention, but after asking around, I was told it really didn't matter. Doing it this was lighter and simpler. I may have to rethink that decision now. Let me ask this... Would having the regulator at the end of the fuel rail cure the air lock problem? The Subie group is having this problem and I think their pressure regulator is at the end of the fuel rail. Maybe someone can do a test for the sake of the group? As of this time I haven't had any problems with heat soaking after running, but I don't have the cowl installed at this time so that could change things.
With that said, I'm in the process of moving my primary injectors back to the intake ports. This will result in two fuel rails (rather than one), and a change in plumbing. Maybe now would be a good time to move the pressure regulator too.
Mark S.
(Tracy's design is looking better and better)
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