N200LZ: EFI Fuel Route

[TMann]

I'm planning on using the Berkut sump solution for my Long-EZ along with a reserve tank in the hell hole (I'm installing Infinity Retracts so this area is available.)

 

Both wing tanks feed into the Berkut style sump (at the same time) with check valves to prevent backflow or cross feeding.

The fuel selector I have in mind is the Andair FS25-20 Duplex Fuel Selector. It allows you to switch your return at the same time you switch your source.

 

My question is this:

If I have my Berkut style (central) sump as the source, can I safely return fuel back to the sump without a problem of pressurizing the sump tank?

 

I have a central point of fueling so I supose I could vent back to that in necessary and avoid dumping fuel overboard.

[Eccentric]

I'm not familiar with the Berkut sump, but that sounds like the system I have. Stock Long-EZ fuel system, the selected main drains by gravity to a sump tank that is bolted to the cold side of the firewall, very low! My tank is made from steel and has two high pressure EFI pumps inside. The fuel return from the engine goes back to this sump tank. The sump tank must be vented, but you don't want it pressurized higher than the mains from forward facing vents. My sump vent is lower (above and behind the passenger's head) and has a very smaller inlet compared to the main tank vents. Sump only holds about a gallon, there is no "fuel heating" as some have theorized. No issues in almost 700 hours of flying.

[mplafleur]

I'm not familiar with the Berkut sump, but that sounds like the system I have. Stock Long-EZ fuel system, the selected main drains by gravity to a sump tank that is bolted to the cold side of the firewall, very low! My tank is made from steel and has two high pressure EFI pumps inside. The fuel return from the engine goes back to this sump tank. The sump tank must be vented, but you don't want it pressurized higher than the mains from forward facing vents. My sump vent is lower (above and behind the passenger's head) and has a very smaller inlet compared to the main tank vents. Sump only holds about a gallon, there is no "fuel heating" as some have theorized. No issues in almost 700 hours of flying.

I never knew this is the Long-EZ system, but it is almost exactly what I planned for my Cozy. The two main tanks will feed the sump. Mine will be bigger as it will take up the hell hole. It will be about 4 or 5 gallons and will contain two in-tank fuel pumps. I will vent the tank and the sump and unused fuel will be returned back to the sump.

[TMann]

I'm not familiar with the Berkut sump.......

The Berkut sump acts as both a sump and the thigh suport structure for the rear seat passenger. It uses multiple check valves from the wing tank to the sump.

 

Because the hell hole is empty (Infinity Retracts free up this space) I will use this for my emergency reserve. With the duplex valve Andair makes, I can switch my tank from Main to Reserve and change the return at the same time. (i.e. from sump/to sump from reserve/to reserve)

[Eccentric]

I never knew this is the Long-EZ system

What I meant was "stock LEZ fuel system" up to the EFI dual-pump sump, which is not part of the stock system. I already had my plane built per plans when I decided to go rotary EFI-EI. So I put the small EFI dual-pump sump where the gascolator is shown in the plans, with EFI fuel return to the sump rather than any fancy valving stuff trying to get fuel back to a main tank. Later I moved the sump to the cold side of the firewall.

 

I don't really like calling it a "sump" because it sometimes creates confusion.

[TMann]

Lance A. (of site guage fame ) had a description of his fuel system. He uses the 'thigh support' sump in his plane. It sounds like this is used on several other designs as well.

 

It is sounding as though running the return back to the sump will not be a problem. I believe the sump will hold just under 2 gallons. I have not run the numbers yet for the reserve tank in the hell hole but it's looking like 5-8 gallons.