The small in the tank high pressure pumps used in fuel injection are not
tolerant
of even small debris. Thus the filter sock on the pickup. once through the
pump there is only the very small micron filter in the injector. So a filter
after the pump is a must, and it needs a slightly smaller micron rating than the
screen in the injector.
Gascolators generally have course screens in the top, and are of no value
in protecting injected systems. OK for carburetted systems.
The pumps should be mounted in the tanks or close to and below the tanks
where possible.
Pushing fuel under pressure is preferred to trying to suck it uphill from a
tank. On a hot day,
and, or, with a length of fuel line close to a heat source, you will boil
the fuel in the line, followed by a quiet period of glider practice.
Notice that modern cars are nearly immune to vapor lock (boiling fuel).
Because the pump is in the bottom of the cool fuel in the tank, pushing the
fuel.
Auto fuel boils more readily than aircraft fuel. So the shortest
suction side run possible is best. Also, for any particular heat load, higher
altitude means less pressure on the fuel surface in the tank, and boiling
may occur.
The race car uses a disposable filter from the parts store (inline can with
push on ends) for about $2.00 each. These on the suction side of two sliding
vane pumps mounted even with the fuel cell bottom. All of the pressurized fuel
goes through a 16 micron filter then to the pressure regulator and the carb. The
regulator is right beside the carb, so the highest pressure fuel is maintained
to as close to the carb as is possible.
Carbs and sliding vane pumps are tolerant of larger debris than are roller
style high pressure pumps.
Lynn E. Hanover