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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.
I actually had another option that I didn't list... #4 redesign my fuel delivery system to mimic the RV Otter. If I understand Tracy's system (correct me if I'm wrong Tracy), it has a facet pump that transfers from one wing tank to the other (hooked to a 7 minute timer), and a high pressure pump on the other wing tank which delivers fuel to the fuel rail. And finally a fuel return back to the second wing tank. Nice thing here is it eliminates the need for a fuel selector valve. It also locates the efi pump nearer the fuel source.
Mark S. (I also like option #2)
At 01:46 PM 5/25/2004 -0700, you wrote:
Mark,
I have worried about this also, but based on your description, I have a question.
It sounds like the line from the filters goes to the regulator, then back to the valve. Does the regulator sit after the fuel rail? Or does the AN-6 line to the injector branch off from the regulator and 'dead end' at the injectors? There is a fellow running an E-racer with the latter system installed and it works fine, but his pumps are below the level of the fuel tanks, at least 1 foot of head on the pumps.
I think the small bypass hole sounds more reliable than a solenoid switch, etc.
Bill Schertz
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For the record, I have two of Tracy's efi pumps, with two efi filters, hooked in parallel. They are mounted low on the fire wall. Upstream is a gascolator and an Andair 6-port selector valve. Downstream of the pumps/filters is a map sensing pressure regulator. There is a -6AN going to the fuel rail, and a -4 return line back to the Andair valve/tank.
I was curious if anyone else has had this happen and what they did to resolve the issue. I have come up with two possible solutions.
1. Tee off the pump output and put an electric solenoid valve in the line and tee the outlet of the solenoid to the fuel return line, past the regulator. Push-button switch on panel would activate the solenoid. If needed, a second or two of activation should relieve the air-lock and allow the pumps to re-prime.
2. Install a bleed line around the pressure regulator with a small metering orifice (.020-.030") that would bleed off any air that might get trapped. (This appears to be the solution the Subaru group is focusing on). This would be a full time bypass. This seems to be the simpler solution.
3. Install a low pressure, high volume fuel pump in one, or both, of the wing tanks. Procedure would be to always keep reserve fuel in this tank.
Any comments from seasoned flyers would be welcomed.
Mark S.
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