I have a question for people with electronic fuel injection systems. My
question involves the tank setup and return lines. On a Cozy with a
20b.
I have a sump tank and I planned on having check valves between the wing
tanks and the back seat sump tank. ( I am using Infinity retracts ) I'm
not
using a tank selector valve. Only a fuel system on/off valve. I
want it
simple yet right. I have 1/2" stainless tubing between the tanks and
1/2"
outlet from the sump. Now I'm concerned about the return line from the
Fuel
Injection. Will the pressure of the heated return lines keep the check
valves from allowing more fuel into the sump? I plan on a vented
system in
all tanks but then worry that any pressure could push fuel out of the
sump
vent line. I planned on having possitive air pressure on the vent lines
during flight by facing the outlets into the wind or "jetstream"
I've got notes from other past questions on this group that suggest the
check valves but I'm not sure they are using EFI and I wonder where they
are
returning the fuel.
Rick Irwin
I'll give my take on your questions Rick, have a few questions of my
own. Where in the system is your fuel on/off located? Are your pumps
external to the sump? This has created problems for others, I suggest
pumps inside the sump. I do not have a check valve between selected main
and sump on my system. How large is your sump? The fuel returning to the
sump (if that's where you choose to send it) is not under high pressure.
I do see merit in your concern that ram pressure on the main tank vents
could force fuel out the sump tank vent. Perhaps the sump tank should be
vented back to a main tank or main tank vent?
I do have check valves external to the sump on the outputs of the two HP
fuel pumps before the outputs join to one enroute to the engine fuel rail.
Perry
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