Fuel Systems

In order for the engine to run properly, the fuel must be:

• mixed with air at 15 pounds per square inch to one part of gasoline

• 15 parts of gasoline to one part air

• one pound of gasoline to 15 pounds of air by weight

• none of these are correct

An air cleaner is essential to engine operation because:

• it keeps out the dirt

• it controls top speed

• the engine cannot run without an air cleaner

• all of these are correct

In the gravity feed system:

• the tank is below the carburetor

• fuel is drawn up by suction

• the tank and the carburetor must be very close

• the tank must be above the carburetor

The float chamber, float and needle valve do the following in a carburetor:

• control the level of fuel

• atomize the fuel

• cause the engine to accelerate

• all of these are correct

The fuel pump in a small engine is a very simple one consisting of:

• intake valve and camshaft

• float and needle valve

• suction pipe and shutoff valve

• none of these are correct

Answer explanation

It consists of a chamber, rubber diaphragm, a spring, and two one-valves which control inlet and outlet.

In its simplest form, a carburetor is:

• a tube with a venturi

• a main jet near the venturi

• a float and needle valve

• all of these are correct

The simple carburetor:

• cannot be used to run the engine

• will allow the engine to run fast

• will allow the engine to run at various speeds

• all of these are correct

A throttle in the carburetor:

• is used to control the speed of the engine

• allows the engine to start easy when cold

• controls the idle mixture

• all of these are correct

The idle jet allows the engine to:

• start easily when cold

• reach top speed quickly

• keep running when the throttle is closed

• run economically

The choke valve:

• is used to control engine speed

• should be opened as soon as possible after the engine starts

• is used to reduce the size of the venturi

• all of these are correct