Chapter 23 Engine Installation - Electronic Ignition & Fuel Injection for SDS EM5

SDS EM-5 manuals are on this page:


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

More SDS info is here:
http://www.sdsefi.com/aircraft.html


I've run two lines from each tank up to a dual gang Andair valve.  The valve controls which tanks the fuel is pulled from and bypass fuel is returned to.

A more modern design would have been to put the pumps in the tanks like they do in automobiles.  This helps cool the motors and submerges the pump in the fuel to help improve efficiency.   A few downsides are there still needs to be a method to switch the bypass fuel into the desired tank.   Openings into the tanks for maintenance are going to add weight and also a likely place for leaks.

The lines in the tanks are positioned in the sumps.   The outlet is positioned near the front bottom of the sump where a drain sump is located.   The return is positioned under the screen with the end of the line pointing upwards.   This should help isolate air bubbles that might be in the system.   The recommended distance between the in/out lines in the tanks is 4".   My configuration is at 7".  Both lines return to the tank under the surface of the fuel to avoid building up static charges.  Another consideration is that cooler fuel should be drawn into the pump, so pushing the warm fuel where it can dissipate heat before returning to the pump and engine is desirable.