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Date: Tue, 3 May 2005 04:33:34 -0700 (PDT)
From: Steve Brooks <prvt_pilot@yahoo.com>
Subject: Re: [FlyRotary] fuel pumps
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
In-Reply-To: 6667
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Paul,

I have the same set up with two EFI pumps.  I have one
primary pump, which comes on with the master switch,
and the 2nd pump is controlled with a switch on the
I/P labeled "boost pump".  I use the 2nd pump for take
off and landing only.  Unless I forget to turn it off
of course. 

Those pumps draw a significant amount of current, so I
don't want both running normally.  I do also have a
shut off switch (locking) on the primary pump.  I turn
it off on shutdown, and let the engine run out of
fuel.  That way the fuel rail is not pressurized, and
it doesn't leak fuel out the throttle body as fuel
seeps past the injectors while parked.

Steve Brooks

--- sqpilot@bellsouth.net wrote:
> Hi all....I need to ask a question regarding the two
> EFI fuel pumps. (I have two MSD pumps, I think they
> are something like 65 psi each).  Should these pumps
> run continuously?  I know that on my automobile,
> when you first turn the key (ignition), you can hear
> the fuel pump run for a few seconds to pressurize
> the system, then it sounds like it shuts off. On our
> aircraft, should they also do this or should they
> run continuously, since the unused fuel is returned
> to the sump tank after the fuel pressure regulator? 
> I know that my MicroTech system has the wire that
> supplies power to the fuel pumps going to a relay
> first, then the power leaves the fuel pump relay and
> goes to the fuel pumps. 
>      I know that most of you have Tracy's ECU
> system, but if I recall correctly, I think that Ed
> Anderson had used an automotive ECU (another brand)
> prior to changing to Tracy's ECU.  Just wondering
> how that system worked, regarding the fuel
> pumps.....constantly running or on demand.
>      Thanks in advance for any and all info you guys
> might have regarding how the EFI pumps are supposed
> to work.  Paul Conner
>