The only modification to Vans standard is replacing the single pump with the

dual, and the extra return plumbing. There was a thread a while ago where a
guy got a dual valve made more cheapy.  You could also use two normal valves
and gang them on a common shaft or with a linkage.

Another excellent, proven option is Tracy's main tank/aux tank system, where
the fuel system draws and returns from one tank, and the other tank just has
an LP transfer pump feeding the main tank.

Ed uses the standard RV system firewall aft (correct me if I'm wrong Ed)
with fuel raill return fuel looping back to a header tank before the HP
pumps (same idea as the Subaru mentioned). Although this system has the
concern of vapour lock due to looping fuel heating up at low power settings,
Ed must have over 350 hours on his, and has operated into Florida heat.

Personally I'd rather have the HP pumps and filters in the chambers under
the floor on the RV-4 than forward of the firewall, as

fuel spraying there

has lees ignition sources.

Regards,
Mark Wrathall

Thanks Mark, I see your point. My idea was to eliminate the high pressure fuel lines from the cockpit area, so I came up with the idea of using an electric six port valve on the engine side of the fire wall. The fuel pumps would be located either in the wing root or in the little fairings that RVs have on the bottom of the fuselage aft of the firewall. The same switch that actuated the electric tank valve would select the apropriate fuel pump. Then I thought 'if the pumps each have anti backflow valves, then why even have a selector valve?' The down side is that you would have to have some way to switch the fuel return to the tanks, and you would have make some sort of method to run both pumps for takeoff and landing. The problem here is that like you mentioned, with full fuel tanks, your fuel return is going to vent overboard from whatever tank the return is going to.

Well, there are several options here. I'd like to avoid having to buy one of those extremely nice but pricey Andair 6 port fuel selectors.

I'm considering having one fuel pump per tank, going to a my fuel filter,which has two inlets. The selector would be a switch right next to return valve. To run both pumps simultaneously, I have a momentary on switch on my throttle. Rich Martin suggested a microswitch on the forward throttle stop, perhaps with a disable switch nearby.

This is getting a little complicated, which might be a sign that I'm going down the wrong path.

Any new word on those manual six port valves that someone found and posted about here?

Brian Trubee

 
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