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Message
I want to know what the pressure is in the line after the fuel
regulator. If it is greater than the pump output pressure of the transfer
pump then I will never be able to transfer fuel. If that is the case I
will have to plumb two extra return lines to the tank.
Hi
Ron,
My system is generally
like Tracy's, though I can't confirm the minute details of his plumbing. I
added one return line to the tank, and use the same line for fuel return, and
transfer pump. I don't believe there's going to be any problem with
this, but mine hasn't been extensively tested. For the most part, my
flights have been so short that I've had no real need to transfer fuel. As
a part of my preflight, I transfer fuel to the feed tank, so that it's about 5
gallons higher than the non-feed tank. I've turned on the pump in flight,
and believe it actually was transferring fuel (gauges are useless), but I
can't say if it was as fast as it would have been if the engine wasn't
running. Eventually, I'll get a better feel for this, and could even test
it on the ground if I ever find myself fairly low on fuel. I could use the
transfer pump to empty the non-feed tank, then add a couple gallons of fuel and
see how long it takes to pump that out. I could repeat the same test with
both EFI fuel pumps on, which would be worst case. I would expect they
would be very close to the same time, but it would be a good test to do some
day.
BTW, I installed my fuel
return fitting toward the top of the removable cover of the tank.
That means that it's often below the level of the fuel, which has caused me
a slight problem. The Facet pump doesn't have a leak-proof check
valve in it, so over the period of a week, fuel will equalize between tanks to
some extent. Tracy has his plumbed like the vent line, to the top of the
outboard end of the tank, so it's almost always in the air-space above the fuel,
so he doesn't have this problem. If I were doing it again, I would
make an attempt to plumb it higher, via a tube inside the
tank.
Cheers,
Rusty (spent the
best weekend we've had building my new supercomputer)
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