AM15 Fuel Pump Notes – January 2018

Our AM15 engine came with two Bosch-044 clone fuel pumps. They are from China and don’t have a manufacturer or part number.  They are labeled MFS for Manta Flight Systems.

We would like to upgrade those fuel pumps and design a redundant system that is safe and effective.
Here are some of our notes:

We’ll likely have the two pumps in parallel, each with their own prefilter, combined post-pump with a T (no checkvalves), and a common post-filter up near the engine, just before the rail.

Electrically we’ll have a 12V/20A key switch (Honeywell 84826) that provides ECU power, a separate SPST fuel pump switch to run the main pump, and then an “Emergency Engine Power” DPST switch that runs the auxiliary pump and provides power to the ECU on a separate breaker that bypasses the key switch.  Start will either be through the key switch, if we pick a three-position one (Off/On/Start) or through a push-button off the ECU circuit.  Alternator field will be from a third switch.

This is all going to be separate from the rest of the aircraft electrical wiring, so the engine can continue running with the master turned off. The only connection through the master contactor will be the main 12V feed up to the starter solenoid.  Alternator output lead will go directly to the battery, with a fuse close to the battery.

Possible pumps to use:

Walbro GSL-393
http://walbrofuelpumps.com/walbro-gsl393-fuel-pump.html

or Walbro GSL-391
http://walbrofuelpumps.com/walbro-gsl391-fuel-pump.html

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