Angier,
My gascolator and boost pump are in the same general area with no
cooling shroud.
My engine driven pump is attached to the hot engine in a hot location on
the hot side of the cooling plenum where it is hot.
In stop and go taxiing and idling on a hot day I have receiving
warnings that the fuel pressure had dropped below 12 psi. This is probably
a result of the vaporization of fuel and consequent pump
cavitation in the engine driven pump that might have been a bit
warm. This problem is always resolved by flipping on the boost pump (it is
getting warmed fuel from the gascolator) and either clearing the problem
immediately or leaving the boost pump on until it is no longer needed.
Hot starts have a similar problem because of the heat soaked engine driven
pump. This problem is reduced by running the boost pump (even with the
mixture at idle cutoff) in order to raise the fuel pressure and put
some of the vapor back into solution.
In "hot" weather (above 70F), the boost pump is turned on during
takeoff and initial climb. It is also turned on during the downwind (or
approach) and left on until I am off the runway.
My engine temps are not too high during these operations (CHTs under 380F,
oil under 210F).
Scott Krueger
AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL (KARR)
Pilot
not TSO'd, Certificated score only > 70%.
In a message dated 2/20/2008 2:22:19 P.M. Central Standard Time,
N4ZQ@comcast.net writes:
As we
all know, everything's a pretty tight fit firewall forward.
Given the low
130 +/- degree boiling point of 100LL, I'm wondering if
I should
enclosed the boost pump/gascolator in a shroud with cold air
directed to it.
I suppose it's possible with low power on a hot day
and short final,
fuel could start to vaporize in this part of the
fuel system resulting
in engine stoppage at just the wrong time. Of
course the boost pump
would be on at this point, but are any of this
group aware of an
instance of power loss due to vaporization at low
power settings?