Gen 3 fuel pump

To answer this question is why the FAA recommends you do a fuel flow test. My Kitfox SS7 with 912uls will flow more than enough fuel with engine off and 15 degree nose-up angle.

Hi James,

Thanks for your reply.  I do have sufficient flow at the low point when checking for water.  I have also placed a 5 gal jug under the drain to empty the tanks of any aging ethanol free auto fuel I use.  I do not have an electric back up fuel pump.  Where I am concerned is if the fuel pump fails.  Will there be enough fuel gravity fed to the engine in level flight to maintain power.  I have a Gen 3 fuel pump on the engine and as I understand fuel will still reach the engine.

Bill

Probably not!

It's always best to have redundancy, especially in the fuel system. We highly recommend you install an electric fuel pump. The Rotax 912 installation manual states the following: The engine manufacturer recommends the use of an electrical auxiliary fuel pump if this is not already required by airworthiness requirements. The electrical auxiliary fuel pump is not just required in case of a malfunction or defect of the mechanical fuel pump, but also provides required fuel supply e.g. in case of vapor formation at high altitudes and temperatures.

See attachment

I do not have a back-up electric pump, although I agree it is a good idea.

As I was trying to say above, the fuel flow test is done by measuring fuel flow out of the hose fitting at the outlet of the fuel pump. With the engine off this simulates a failed, non-operating, fuel pump in a climb attitude (worst case). The gravity flow from the wing tanks thru the system should be enough to feed the engine at full throttle. If this test is passed, there certainly will be enough fuel flow to maintain power in level flight. I believe this test is very important, and should be done before the first flight. It will show if there are any excessive restrictions or undersized fuel hoses in your system.

James, if I hear you right you are saying to disconnect a fuel line just ahead of the Carburetor and see if the fuel flow is sufficient.  Is this correct?