Fuel Metering

Question 1

What are the most common types of fuel metering systems used on small reciprocating engines

Answer 1

Float-type, pressure, and direct fuel injection systems

Question 2

What function does the mixture control perform

Answer 2

Controls the fuel/air mixture

Question 3

What generally causes spark plug fouling

Answer 3

an excessively rich mixture at idle

Question 4

What is the purpose of an accelerating system

Answer 4

It provides an increase in fuel flow in the Venturi to enrich the mixture

Question 5

What is a carburetor economizer system

Answer 5

provides a richer mixture at high power settings

Question 6

When the mixture is placed in the idle cutoff position, a slight rise in rpm is noted prior to the engine decelerating. What does this indicate

Answer 6

Idle mixture is set correctly

Question 7

Why should engine r.p.m be accelerated periodically when making carburetor adjustments

Answer 7

To clear the engine

Question 8

What maintains the fuel pressure injection carburetor

Answer 8

Engine driven fuel pump

Question 9

What purpose do turbine engine fuel control units serve

Answer 9

They automatically meter fuel to the engine

Question 10

What are the two basic types of turbine engine fuel control units

Answer 10

Hydromechanical and electronic

Question 11

What do turbine engine fuel spray nozzles do

Answer 11

They inject fuel into the combustion area

Question 12

What are the different engine indications used for trimming a turbine engine

Answer 12

Either EPR or r.p.m is used depending on engine

Question 13

What type of pump can very the amount of fuel discharged regardless of speed

Answer 13

A variable displacement pump

Question 14

What is used to keep water, sediment, and foreign matter out of the carburetor

Answer 14

Main fuel strainer

Question 15

What type of engine driven fuel pump is widely used other than gear or piston pumps

Answer 15

Rotary vane type

Question 16

What is the purpose of a pressure relief valve in a constant displacement pump

Answer 16

It returns left over fuel that is not used by the engine to the inlet side of the pump

Question 17

What function do fuel boost pumps perform

Answer 17

Supples pressurized fuel to the fuel pump, which helps prevent vapor lock and cavitation

Question 18

What is a commonly used type of fuel boost pump

Answer 18

Centrifugal type

Question 19

Name two categories of turbine engine pumps

Answer 19

Constant and variable displacement

Question 20

What category is a gear type pump classified in

Answer 20

Constant displacement

Question 21

When performing an external inspection of an engine driven fuel pump, what should you look for

Answer 21

Leaks and security of mounting

Question 22

What is the purpose of a shear section of the driveshaft in a dual element constant displacement pump

Answer 22

If one Element seizes it allowing the other element to continue to operate

Question 23

What is the purpose of a duplex fuel nozzle

Answer 23

Discharges two different spray patterns

Question 24

What purpose do fuel selector valves serve

Answer 24

Allow tank and engine selection, and provide a means for shutting off fuel flow

Question 25

What will be the result of using excessively rich idle mixtures

Answer 25

Cause carbon fouling of the spark plug

Question 26

What position do you place the mixture control of a pressure injection carburetor to stop the engine

Answer 26

Idle cutoff position

Question 27

What is the typical fuel pressure in a float type carburetor

Answer 27

3-5psi

Question 28

What are three types of carburetor icing

Answer 28

Throttle, impact, and fuel evaporation icing

Question 29

What are some of the sources used to heat the fuel in a turbine engine fuel system

Answer 29

Bleed air and engine lubricating oil