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

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