Fwiw, mine was pulling through the elec fuel pump, but I have re-hosed it
and now added an andair checkvalve in parallel with the pump. Common
practice, and removes any fuel pump restriction.
Will be interesting to see if that change reduces the drop.
Cheers
PeteZ
On Fri., Apr. 23, 2021, 4:30 p.m. Jeffrey Williams, <
jeffwill55@sbcglobal.net> wrote:
> This has caused me to think a bit.
>
> The Europa builder=99s manual shows the fuel going from the fuel se
lector to
> the electric fuel pump and then to the engine=99s mechanical fuel p
ump. Is
> that how it is set up?
>
> If so, does the fuel get pulled through the electric fuel pump by the
> mechanical fuel pump when the electrical fuel pump is turned off? That
> seems like it would cause variation at that point.
>
> Various aircraft builder=99s books from the EAA show a parallel sys
tem for
> low-wing aircraft. Those diagrams make sense to me. In other words, they
> show the fuel being provided by a parallel fuel system, with fuel lines
> going from the fuel selector to both 1) the electric fuel pump and then t
o
> the carb, *and * 2) to the engine=99s mechanical fuel pump and to t
he carb.
>
> That way, if the mechanical pump quits, the electrical pump doesn
=99t have
> to try to push fuel though the mechanical one to get to the carb. And, th
e
> mechanical pump doesn=99t have to pull fuel through the electric fu
el pump if
> the electric fuel pump is off or it quits.
>
> Which way *should* this be set up, and and if you think it=99s the
way
> shown in the Europa builder=99s manual, why?
>
> Jeff Williams
> Builder A157
>
>
> On Apr 22, 2021, at 10:19 PM, Griffo <scangriffin@bigpond.com.au> wrote:
>
>
> Hi Dave,
>
> Hi,
>
> It=C3=A2=82=AC=84=A2s good that you are taking precautions to avoid
having the electric
> (boost/back up) pump mask/hide a failed mechanical fuel pump.
> However, I would question the merit of leaving your electric pump on at
> all times, as I would expect a pump, so operated, to become a service ite
m
> replaced at ?? hours of operation (as the mechanical pump has a recommend
ed
> service life).
> I only use my electric pump =C3=A2=82=AC=9C prior to engine star
t (off for start) to
> check fuel pressure/availability. On again, for take-off. Off when safe
> height above terrain achieved. On again, when downwind for landing.
> Your engine will run perfectly without the need for the electric pump,
> which should only be used when you have a mechanical fuel pump failure, a
t
> critical times, when fuel starvation is not a good option.
>
> --------
> 46
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=501476#501476
>
>
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