EFI Fuel Return Line Plumbing

[rv6ejguy]

The main aircraft page is at: http://www.sdsefi.com/aircraft.html

Some of the RV specific stuff is on the -6A page at:

http://www.sdsefi.com/air9.html

I've started a page on the new RV10 project as well at:

http://www.sdsefi.com/air46.htm

Not much on here yet but I'll be detailing the Subaru EG33 conversion mods once the major airframe parts are done.

I have Earls mesh type filters between the low pressure pumps and the header tank and between the header tank outlet and the high pressure pump inlets, same type. These are about 4 X 1 inches, cylindrical.

One Facet and one high pressure pump must be on at all times while the engine is running. The Facets put out 30 gph at around 4-6 psi. Excess fuel is passed out the top of the header tank back through the Andair fuel selector to the selected tank. Excess fuel from the rail is also fed to the top of the header tank first before flowing back to the tanks.

The Bosch high pressure pumps have an internal check valve so either or both can be used. While some may consider this setup complicated, it does have full redundancy and is flight proven in bank angle up to 80 degrees, uncoordinated turns and extreme pitch maneuvers. Some of the other non- header systems I've seen give me the willies. Not sure if they will feed with low mounted fuel tanks with low fuel levels in uncoordinated turns.

Returned fuel always enters tanks at the top to allow entrained air or vapor to pass into the air and not be picked back up into the inlets. If you suck air or vapor with EFI on the high pressure pumps, the engine will stop right now!

[rv8ch]

Thanks a lot for the information, and the links.

[copterdoc]

Thanks everyone. It seems I'm on the right track. I was looking at tubing on Aircraft Spruces' web site. Are you guys using "Versatube" or one of the heat treated EXPENSIVE tubings? The Versatube has plenty of working pressure and will be my choice unless someone here knows better. I would think the harder tubes would be prone to cracking when bending or flaring. Which brings me to another question. Maybe this should be in the tools forum but which flaring and tubing benders have proven to be the best for us RVbuilders? Doug let me know if I'm taking this too far off subject and thanks for a Great web site.