What does not show in the drawing are check valves on each
vent on the sump. That allows air to leave the sump but not enter via the vent
line.
# So pressure relief for the sump has to
come thru the lines from the wing tanks?
>If the fuel filter starts to plug, the resulting low pressure on
the suction side of the pump will likely result in vapor lock especially if the
pump is in the engine compartment where it is hot.
The filter before the pump is actually a gascolator. It
has a very large area and is easy to service and drain. The pump is prior to
passing fuel through the firewall per Velocity design.
# I thought that might be a Gascolator in
the drawing, but the change in color made me think that both the Gascolator and
the pump are in the engine compartment. I have a boost pump that is prior
to the Gascolator, which is prior to the dual FI pumps, then a filter after
that in case one of the FI pumps shells out.
> Filters are best after the pump so they are under pressure and not
vacuum.