Barry Knotts wrote:
I wonder what other listers have done for that section of pressurized
flexible fuel hose within the cabin (for an -IV).  I might even consider
having a professional make a hose.  Or maybe there are off-the-shelf hoses I
could use. (Aeroquip?)

Barry,
Aeroquip can easily make you a high quality hose for this. If you go this
way, be sure to measure the length needed very carefully, as there is little
room for it to flex--or better still, mount the pump after you have the hose
if you're not past that stage of construction.

Having said that, the pump output pressure is not high relative to the
capability of standard aircraft hoses/fittings, and the parts you have to
make your own line should be more than adequate. In my opinion, lines on the
suction side of the pump are actually more critical than those on the output
side. If the output side leaks, you'll easily smell, and possibly see the
gasoline quickly. A "vacuum leak" however is insidious and can be very hard
to find.

You see a lot about pressure testing the pitot system, but folks rarely
discuss testing the fuel lines. First of all, it's more difficult because
you really can't easily do a complete "end to end" test, but I think this is
one of the more important "test" items during final assembly. If you build
your own hoses/lines, and test them under fuel pump operating pressure +50%,
you should expect that they will work reliably, and last a long time.
Consider also doing a vacuum test on the lines--unconventional, but a bit
more reassurance if you're really concerned, and relatively easy once you
have them set up for pressure testing.

Hope this helps.

Bob Pastusek