Module 4: Small Engines Fuel Systems
Muffler shell
A ________ is a stamped metal housing that reduces exhaust noise and secures the catalytic element directly in line with the exhaust stream.
throttle
A ________ plate is a round moveable disk that pivots on a shaft, regulating air and fuel flow inside a carburetor.
choke
A ___________ plate is a flat plate placed in the carburetor body between the throttle plate and air intake that restricts air flow to help start a cold engine.
vent
A bowl ________ is a passage drilled into the carburetor connecting the fuel bowl to the atmosphere.
8; 18
A gasoline molecule contains ______ atoms of carbon and ________ atoms of hydrogen.
Venturi
A multiple-barrel carburetor is a carburetor that contains more than one _________.
No Smoke
An engine equipped with an internally vented carburetor will exhibit ______ form the exhaust system if the air cleaner becomes more than 70% clogged.
bimetal choke spring
During a high ambient or engine temperature, the _____ expands to assist in the opening of the choke plate.
False
T or F: A Briggs & Stratton engine equipped with a Vacu-Jet Carburetor should be adjusted with the fuel tank full.
True
T or F: A check ball is a component that functions as a one-way valve to allow fuel to flow in one direction only.
True
T or F: A completely blocked high speed air bleed can commonly cause an engine to run very rich under load.
False
T or F: A down draft carburetor that has the air intake opening below the fuel bowl.
False
T or F: A dry bulb and a wet bulb primer system work in conjunction with the choke plate to provide easy cold starting of the engine.
True
T or F: A float is a carburetor component that floats at a specific level to regulate the opening and closing of the needle and seat.
False
T or F: A hydrocarbon molecule is a molecule held together by a tight bond between hydrogen and carbon atoms that occurs naturally in all fossil fuels.
True
T or F: A needle and seat provide a tapered seal to regulate the flow of fuel into the carburetor.
False
T or F: A side draft carburetor is a carburetor that has an air intake opening below the fuel bowl and parallel to a horizontal plane.
True
T or F: Air density is the mass of air per unit volume.
True
T or F: Alcohol is a fuel, or fuel additive, used to enhance the octane rating of gasoline.
False
T or F: An updraft carburetor is a carburetor that has the air intake opening above the fuel bowl.
True
T or F: Check valve is a valve that allows the flow of material in one direction.
False
T or F: Engine horsepower decreases by 5.5% for each 1000' above sea level.
True
T or F: Filter mesh screens are rated at the number of openings per sq. inch.
True
T or F: Gasoline blended for use in the winter is highly volatile compared to gasoline blended for use in the summer.
False
T or F: HC emissions are caused by unburned, partially burned, or raw fuel.
True
T or F: In the 1970s, ethyl alcohol was used as an alternative fuel and renewable energy source.
True
T or F: LPG requires higher ignition temperatures and burns slower than gasoline
True
T or F: Liquid gasoline is not flammable.
True
T or F: Most catalytic converters used with small engines are monolithic converters designed specifically to reduce hydrocarbon and CO exhaust emissions.
False
T or F: Nitric oxide is more toxic than other oxides of nitrogen.
False
T or F: Small black spheres present in the fuel bowl are actually tiny pieces of hardened petroleum.
False
T or F: Temperature outputs are used to determine final fuel delivery quantity based on what previous testing has shown to be optimal.
False
T or F: The air-fuel ratio of an LPG-fueled engine is affected by altitude changes.
True
T or F: The fuel cup is a reservoir located high inside the fuel tank.
True
T or F: The most common fuel used in small engines is gasoline.
False
T or F: The octane rating of a fuel is a good indicator or how much power the fuel can deliver during oxidation.
True
T or F: The stoichiometric ratio for common pump gasoline is 14.7:1
True
T or F: True idle is the carburetor setting when the throttle plate linkage is resting against the idea speed adjusting screw after idle air-fuel mixture adjustment.
False
T or F: Vaporization is the process in which a liquid is sufficiently cooled to change states of matter from liquid to a vapor.
True
T or F: Volatility is the propensity of a liquid to become a vapor.
14.7
The most efficient and complete combustion of gasoline occurs when there are ______ parts atmospheric air for every 1 part fuel.
Nitrogen oxide
The three main undesirable compounds generated in exhaust gases from small engines are hydrocarbons, carbon monoxide, and _______.
Increases the Venturi size
The throttle plate in a Briggs & Stratton carburetor
Carbon monoxide
_______ is a product of incomplete combustion and is formed when and HC molecule is broken during combustion with a deficiency of available O2.
Carbon Dioxide
_________ is a heavy, colorless gas that does not support combustion.
