My ES has a momentary prime switch along with a low and high boost
switch.
I use the high boost to pressurize the fuel system before starting. I
use the prime position for a couple of seconds before doing a cold
start. I do not use it on hot starts.
I use low boost to clear the injector lines of any vapor when doing a hot
start. I turn it off for the start. After the engine starts I turn the
low boost back on for about 30 seconds to prevent vaporization. Then the
pump is off for all operations.
(Early on I would use the high boost pump to cool the fuel lines for a
minute or so before a hot start. Eventually, I found that I could get
better results by setting mixture full rich and then using low boost to clear
and pressurize the injector lines. I can actually hear when the vapor
clears and the lines develop pressure. The pump begins to labor and the
sound gets deeper. Hot starts are no problem.)
I have experienced a loss of engine driven fuel pump while on the
ground. Low boost kept the engine running but in no way could the plane
have been flown. Way too rich.
I once used the low boost in flight when trying out tank switching
procedures. Low boost made the engine run extremely rough. I have
trouble thinking there is a ever a time to run the pump in normal flight
operations.
My $.02. No flaming please. This stuff works really well for
me.
Jim Scales
N98AF
Angel's Playmate
800 hours
Low
Boost - switched on at or above 10K feet and run for the duration of
the
flight at that level to provide added purging of vapors or bubbles
that
might exist in the lines
High Boost - Prime at
startup.
Ok, now, I've also heard that you use High Boost any time you
loose an
engine driven fuel pump. Will low boost
suffice?
I've found a couple of switches that I could replace the
single with that
will allow switching to low and locking out high unless
placed there, or I
could go to an ON-ON-ON type without the
momentary.
So, could you splain to me, what the various boost modes are
or if there is
another compromise that I haven't thought of with one
switch.