Fuel pump setup?

by Kris Hansen in 912 / 914 Technical Questions 5 days ago

I have a 914 installed on a KitFox S7 and even though I have gravity fuel feed to the engine, if both my fuel pumps fail and the throttle is set above a high idle, the engine will sputter and quit. I know I can’t get full power without the fuel pumps but I’m getting much less and the engine is sputtering and quitting without the pumps at with much of a load on the engine. My fuel pumps are on the battery bus so if I have an electrical failure I can only fly as long as the battery can power the fuel pump(s). Is there a better setup with respect to fuel line size and my battery being the only thing standing between me and an engine failure?

Re: Fuel pump setup?

by Ken Ryan » 5 days ago

Ken Ryan

28 369 962

The 914 is an electrically dependent engine. At least one fuel pump needs to be working. One way to approach this is to install the optional belt driven alternator to power the battery bus (and the auxiliary pump) and wire the main pump directly to the flywheel generator, using it only to power the main fuel pump. Now you have three independent power sources: flywheel generator, belt driven alternator, and battery.

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Re: Fuel pump setup?

by Kris Hansen » 5 days ago

Kris Hansen

1 1 2

Thanks Ken!

The airplane has the belt driven alternator but it was installed later and the electrical configuration of the pumps remained the same, both on the battery bus. I think I'll be changing the electrical configuration of the pumps to the way you described.

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Re: Fuel pump setup?

by Rotax Wizard » 5 days ago

Rotax Wizard

2 933 4.03k

Hi all

please look at the installation manual. The pumps need to be split so they get power from 2 sources not one. Run 1 from BAT buss and the other from your generation source. If you are not using the onboard generators and only the belt driven one it still works the same. 1 from the BAT and the other from your Alternator.

The concept is if one source fails the other should still work. Be sure to run the pumps in series not parallel.

Cheers

40756_2_914 dual pumps electrical.jpg (You do not have access to download this file.)

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Fuel pump setup?

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