Hi Remi
"If your fuel pumps are installed below the baggage bay as instructed by
Europa, they will always be below the fuel level, unless your tank is
almost empty."
My Fuel 914 pumps are mounted below baggage bay area. Lets raise the
Gasculators to the top of the cockpit for 1 minute. As long as no air is
in line and there are no air leaks, it is true if the fuel level is above
the inlet of the fuel pump it will be OK, but if you open the drain, air
will be pulled in and air not fuel will be sucked in easier than fuel. Now
lets move the Gasculator to where I have it, right on the floor of fuse
aft of the baggage bay ribs, you need fuel level above the outlet of the
Gasculators to not let a leak in the drain cause grief. Granted for most
part it will not be a problem, but you can pretty easily get level I feel
can be critical if you get an air leak, nose low during landing with low
fuel, running on main of tank and right hand pattern would put outlet of
Gasculator above fuel level.
I am not trying to scare anyone, just keep in mind that a leak in fuel
filter or Gasculator drain besides being a bad thing to leak fuel, could
cause problems with fuel delivery. I want to make light that the
Gasculator drain has more of a chance of leaking than a filter and that
although chances of actually having your engine play Silent Night because
of a air leak is low, none the less at least be aware that drain or drains
can introduce air, so if you see a leak at all, fix it.
The little Pierburg fuel pumps create quite a squirt. There is no question
that even if you had fuel level slightly above gasculator outlet (which is
at the same height as inlet) you will be putting entire feed upstream of
the inlet of the fuel pump at a slight negative pressure. I fooled with
placing pick up of fuel close to surface of fuel, and it creates a
whirlwind and sucks in air. I tried it with level a little above
Gasculators and below.
Try drinking through a straw that has a mini hole in it your favorite
beverage very fast with level of liquid slightly higher than your mouth.
Especially at full power, the Pierburg/s can just about provide the
pressure needed to crack Fuel Pressure regulator and just a little
reserve. If Wastegate gets stuck and you go over max boost, crack pressure
will not be reached and motor will quit, then less boost, fill carbs and
get power back until it quits again. Introduce not much air at full
throttle and I suspect crack pressure will not be met with a proper
functioning wastegate. Just this little tiny bit of air plays hell with
pumps ability, it cavitates and pressure goes way down.
Go ahead, lift up tail of your plane next time you need fuel and turn on
pump and open drain a little, then holding drain same amount opened have
someone turn off pump.
Please report your findings.
Ron P.
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