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DA40 Fuel Pump Operation

Posted: Sat Mar 10, 2018 12:32 pm
by DiamondMike1
For those flying the DA40, the POH specifies turning the electric fuel pump on before doing the run up.

It seems to me that it would be prudent to do the run up with the electric fuel pump off to determine whether the engine runs satisfactorily on the engine driven pump alone. The electric pump could then be turned on during the before takeoff checklist.

Does anyone here do the run up with the electric fuel pump off?

Thanks.

Re: DA40 Fuel Pump Operation

Posted: Sat Mar 10, 2018 4:22 pm
by Rick
I've never done a run up with the electric fuel pump on in a DA40. Ever. I completely agree with your reasoning. My wife is also taking lessons in our DA40, and has never been told to use the fuel pump during the run up.

Re: DA40 Fuel Pump Operation

Posted: Sat Mar 10, 2018 4:30 pm
by Steve
Same here - never do the runup with the electric pump on (my checklist doesn't say to). I try to use the electric pump as little as possible. I just use it on takeoff to 1000' AGL, and in the pattern to land. I still have my original electric pump after 17 years (hope I didn't jinx myself).

Steve

Re: DA40 Fuel Pump Operation

Posted: Sat Mar 10, 2018 7:04 pm
by Don
I agree with the same logic as others here. I never do the run up with the pump on. After my 2000 RPM mag check, I also bring the throttle back to full idle for a moment to make sure the engine does not stall out at very low RPM.

Re: DA40 Fuel Pump Operation

Posted: Sat Mar 10, 2018 7:31 pm
by Rich
For a couple of the below obvious reasons, it's actually counterproductive to have the electric pump on during run up. I do make sure it's running on takeoff, however. A power loss right at takeoff can be lethal: Witness the recent SR22 fatal crash at Montgomery field (San Diego). It may or may not have been a fuel pump problem, but it seems clear it was a power loss (in an almost-new airplane) right at the worst possible time that was the triggering event.

Re: DA40 Fuel Pump Operation

Posted: Sat Mar 10, 2018 8:56 pm
by gordsh
During my checklist execution the fuel pump is turned OFF after the engine starts (for a normal start). The fuel pump stays OFF during [Taxi] & [RunUp] portion of the checklist and then is turned ON in the [Before Takeoff] portion of the checklist.

Re: DA40 Fuel Pump Operation

Posted: Sun Mar 11, 2018 12:19 pm
by ThomasD
I agree with Gordsh and others - I do the same. (Plus pump on at final approach as well.)

FYI one thing that I do not do [which is recommended in the POH] is to switch on the fuel pump when changing tanks in flight, if I am 3,000' or above.
I have never had a hiccup of the engine when just switching in-flight left-right or vice-versa without the pump on, so I don't do so (as the pump appears to have a quite limited life).

Re: DA40 Fuel Pump Operation

Posted: Sun Mar 11, 2018 2:33 pm
by CFIDave
Just to add to the responses above (which I agree with), the original Dukes electric fuel pumps installed in DA40s before around 2009 typically failed every 300-400 hours, so pilots learned to turn on the pump as little as possible. The Weldon electric fuel pumps on newer DA40s have proven to be more robust.

Re: DA40 Fuel Pump Operation

Posted: Sun Mar 11, 2018 3:39 pm
by gordsh
Another thing I should mention is that when practicing circuits I leave the pump ON all the time...as long as I am just doing [takeoff] - [downwind] - [base] - [final] - [landing]....over and over again.

What do you think about that scenario? I just found it too much for me to turn the pump [OFF] once I start [downwind] and then turn it back ON during [base to final]. Similarly when doing circuits I leave the prop full forward.

Re: DA40 Fuel Pump Operation

Posted: Sun Mar 11, 2018 3:50 pm
by CFIDave
gordsh wrote:I just found it too much for me to turn the pump [OFF] once I start [downwind] and then turn it back ON during [base to final]. Similarly when doing circuits I leave the prop full forward.
By doing this you're cheating yourself out of learning the "muscle memory" cockpit flows experienced when flying in the pattern/circuits. You need to cycle the electric fuel pump and prop control (red knob) after/before takeoffs and landings so that their operation becomes ingrained in your memory for ALL takeoffs and landings.