FUEL METERING SYSTEMS Flashcards
What is the purpose of strainers in a fuel system?
They are used to prevent foreign matter from entering the carburetor
What is the purpose of fuel selector valves?
They provide a means of shutting off fuel flow, for tank and engine selection, for crossfeed, and
for fuel transfer
What should be looked for when inspecting an engine-driven fuel pump?
Look for fuel leaks and security of mounting
What is the purpose of an engine-driven fuel pump?
The engine-driven fuel pump must deliver a continuous supply of fuel at the proper pressure at
all times during engine operation.
What type of fuel pump is generally used with large reciprocating engines?
A positive-displacement rotary vane-type pump
What happens to the excess fuel not required by the engine in a constant displacement pump?
The pressure relief valve opens and the fuel is routed back to the inlet side of the pump
What is the most common type of fuel boost pump?
The electrically driven centrifugal-type pump
What is the purpose of the bypass valve in the engine-driven fuel pump?
The bypass valve provides a path around the pump vanes for starting the engine and to allow
fuel to bypass the pump in case of pump failure
What is the purpose of using boost pumps in a fuel system?
Electric boost pumps are used to supply fuel to a pressure carburetor during engine starting
and in case of engine-driven pump failure. However, a main function of a boost pump is to keep
the pressure on the suction side of the engine-driven pump from becoming low enough to
permit the fuel to boil when operating at high altitudes.
What are the three general causes of vapor lock?
They are low fuel pressure, high fuel temperatures, and excessive fuel turbulence
Turbine engine fuel pumps may be divided into what two distinct systems categories?
Constant displacement and variable displacement
What category is a turbine engine-driven gear-type pump?
Constant displacement
What type fuel pump can be made to vary the fuel flow at any speed?
A variable displacement pump
What part of a gas turbine engine fuel system is very susceptible to the formation of ice?
The fuel filter
How is the engine fuel system protected from ice formation?
By the use of fuel heaters
