Automotive Fuel system

AUTOMOTIVE FUEL SYSTEM
GROUP NAMES:
ABDINAASIR AHMED ABDIRAHMAN (ID: 21)
ABDIRAHMAN ALI MOHAMUD (ID: 24)
ABDULLAHI HASSAN ADAM (ID: 39)
This project report submitted in partial fulfilment of the
Requirements for the machine tool
Course
Faculty of Engineering
Somali National University
NOVEMBER 2019

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Abstract
The automotive users have been growing roughly in parallel to the human population
growth. A large part of energy consumption is in form of engine fuels. Automotive have more
systems such as transmission system, steering system, suspension system and fuel system. In this
project we will talk about fuel system in automotive. The fuels used in modern high speed
automotive engines are derived from the heavier residues of the crude oil left over after the more
volatile fuels, such as gasoline and kerosene, are removed during the refining process. The large,
slow running engines used in large automotive will burn almost any grade of heavy fuel oil. In
contrasts with smaller, high speed engines that require a fuel oil that is as light as kerosene.
Fuel systems vary from engine to engine, they have to supply fuel to the combustion
chamber taking the fuel from tank and control the amount of fuel supplied in relation to the
amount of air. The engine intake system is where the fuel is mixed with air, atomized, and
vaporized. Then it can be compressed in the engine cylinder and ignited to produce energy or
power. Although internal Combustion Engines are those engines in which combustion of fuels
takes place inside the engine and hence the chemical energy is converted in to thermal energy,
which is further converted into mechanical work.
In modern automotive fuels, a combination of several chemical additives is used in order
to meet the desired performance level of the fuel. These chemical additives improve properties of
fuels that cannot be obtained through the refining processes.

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Table of Contents
Abstract............................................................................................................................................ i
List of Figures................................................................................................................................ iv
List of Tables ................................................................................................................................. iv
Chapter one..................................................................................................................................... 1
1.1 Introduction........................................................................................................................... 1
1.2 History of Automotive fuel system....................................................................................... 4
1.3 Classification of Fuels........................................................................................................... 6
1.4 Characteristics of fuels.......................................................................................................... 8
Chapter two................................................................................................................................... 11
Fuel system components............................................................................................................... 11
Chapter Three................................................................................................................................ 16
3.1 Fuel Additives ..................................................................................................................... 16
3.2 Types of fuel additives........................................................................................................ 20
3.3 Additive Compositions........................................................................................................ 23
CONCLUSION............................................................................................................................. 24
REFERENCES ............................................................................................................................. 25

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List of Figures
Figure 1. 1 Main types of motor/engine fuels................................................................................. 7
Figure 2. 1 Fuel tank ..................................................................................................................... 12
Figure 2. 2 Fuel filter .................................................................................................................... 13
Figure 2. 3 Main components of fuels system .............................................................................. 15
List of Tables
Table 3. 1 Additives of gasoline fuels and their functions ........................................................... 18
Table 3. 2 Additives of Diesel fuels and their functions............................................................... 19

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Chapter one
1.1 Introduction
The Automobile can be considered, without any doubt, as one of the greatest invention of
the humankind. Its usage deeply modified the way that people move and transport its loads.
Petroleum-based fuels have been used to power automotive vehicles and industrial production
for well over 100 years. Petroleum is one of the most important fuels derived fossil energy
sources. Currently, global annual energy consumption is about 12.2 × 10E9 tons of crude oil.
Energy consumption is expected to increase to 17.5 × 109 tons of oil by 2035. The reserves of
oil, gas, and coal that we depend on are therefore declining, and oil production is becoming ever
more expensive, and causing significant environmental impact as well [1].
The industrial sector uses more energy than any other end-user sector, and currently it
consumes about half of the world’s total delivered energy. Huge amounts of energy are
consumed in industries. The transportation sector follows the industrial sector in world energy
use, and it is of particular interest worldwide, as extensive improvements are being continually
made in the quality of engine fuels [2].
The automobile population has been growing roughly in parallel to the human population
growth. But in the developing world, the automobile population growth is becoming almost
exponential, due to effect of faster economic growth. Globally, the number of vehicles on the
road reached 1 billion by 2011. The growth is being fueled primarily by the rapidly expanding
Asian market, which will see 5.7% average compound annual growth in vehicles in operation in
the next three years. Asia will account for more than 23% (231 million vehicles) of global
vehicles in use by 2011. Thus every seventh person in the world will have a vehicle by 2011.
Europe and the Americas will account for 34% and 36% of the global share of automobiles by
2011, respectively. The Americas and Western Europe will continue to see approximately 1.3%
and 2.0% compound annual growth in the next three years respectively, while Eastern Europe’s
vehicle population growth rate is forecasted to be 4.3%. With the growth in the number of
vehicles, especially passenger cars with internal combustion engines, fuels consumption has
gone up significantly. This has had a deleterious effect on the environment [3].
A large part of energy consumption is in form of engine fuels. Fuels for internal
combustion engines produced from primarily sources are composed of combustible molecules.

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Heat energy is a derivative of fuel’s oxidation, which is converted to kinetic energy. Different
gas, liquid, and solid (heavy diesel fuel, which is solid below 20 °C) products are usable as
engine fuels. These fuels are classified as crude oil based—namely gasoline, diesel fuels, and
any other gas and liquid products —and non-crude oil based—namely natural gas based fuels—
compressed natural gas (CNG) and dimethyl-ether—biofuels, like methanol, ethanol, any other
alcohols and different mixtures of them; biodiesel; biogas oil (mixtures of iso- and n-paraffins
from natural tryglicerides). Liquefied petroleum gases (LPG), which can be crude oil or natural
gas based, and hydrogen are derivatives from different fuel sources [4].
Over the years fuel specifications have evolved considerably to meet the changing
demands of engine manufacturers and consumers. Both engines and fuels have been improved
due to environmental and energy efficiency considerations. New processes have been developed
to convert maximum refinery streams into useful fuels of acceptable quality at reasonable
refinery margins [5].
Gasoline and diesel fuels have been preferred in the development of engine technology.
The price of crude oil is also often at a level that makes petroleum–based fuels in engines
desirable for economic reasons. Whenever crude oil prices do rise, the issue of alternative fuels
comes up but the discussions and investigations get dropped out soon after crude oil prices settle
down. The oil crises of the 1970s and 2008 reflect this tendency. However, oil is not going to last
forever, and it is also not going to be exhausted in the near future. So, while the use of
petroleum-based fuels and lubricants may continue in the current century, it is likely that a
significant decrease will occur after crude oil usage peaks. The application of alternative fuels
will find a place wherever cost–benefit analyses permit or wherever regulations force their use
[6].
Automotive fuel system stores and supply fuel to the engine. The engine intake system is
where the fuel is mixed with air, atomized, and vaporized. Then it can be compressed in the
engine cylinder and ignited to produce energy or power. Although fuel systems vary from engine
to engine, all systems are the same in that they must supply fuel to the combustion chamber and
control the amount of fuel supplied in relation to the amount of air. The fuel is stored in the fuel
tank and the fuel pump draws fuel from the tank. It then travels through the fuel lines and is
delivered it through a fuel filter to the fuel injectors (carburettors and throttle body injection were
used on older vehicles). As the fuel is delivered, the final conditions for providing complete

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combustion are atomization and the spray pattern of the fuel. Atomization is accomplished as a
result of the injection pressure, due in part to the diameter of the holes in the injector. The
spacing, angle and number of holes in the injector tip determine the spray pattern [7].
Internal Combustion Engines are those engines in which combustion of fuels takes place
inside the engine and hence the chemical energy is converted in to thermal energy, which is
further converted into mechanical work. Internal mixture formation occurs in the cylinder of an
internal combustion engine. The air is inducted through the piston and compressed, and then the
fuel is injected into the compressed air at a suitable time. The air-fuel mixture becomes an
ignitable composition within certain ranges that leads to the ignition of the mixture at a
corresponding temperature. Combustion is to be understood as chemical reactions in which a
substance releases heat (exothermic reaction) while bonding to molecular oxygen (oxidation).
Combustion starts with ignition of the fuel [8].

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1.2 History of Automotive fuel system
The first gasoline-fueled, four-stroke cycle engine was built in Germany in 1876. In
1886, Carl Benz began the first commercial production of motor vehicles with internal
combustion engines. By the 1890s, motor cars reached their modern stage of development. In
fact, the models of that decade were so successful that there has been no fundamental change in
the principles of the ordinary automobile engine since that time [9].
It took several more years for the internal combustion engine to sweep the American
market, however. General conditions, such as the expansiveness of the nation, the lack of decent
roads, and the relatively well-developed urban transit system, worked against adoption of any
and all motor vehicles for a time. Mass production of gasoline-powered cars, however, brought
to the market a vehicle that was modestly priced, easy to maintain, relatively fast and powerful,
able to travel long distances, and fueled by a cheap, abundant, widely-available source of energy.
Before the era of the Model T, gasoline-fueled vehicles had stiff competition from steam-driven
and electric cars. In fact, of the 4,200 cars built in the United States in 1900, only one-fourth
employed internal combustion engines. And of the approximately 8,000 automobiles on the road,
most were steam-driven. Steam had been used as early as 1769 to power a road vehicle. French
Army engineer Nicholas Joseph Cugnot designed a three-wheel truck for hauling artillery.
Experimentation with steam-powered vehicles began in the United States in the 1780s primarily
in the Northeast. Into the nineteenth century, however, steam-engine technology tended to focus
on locomotives rather than cars [9].
Particularly noteworthy in the United States were steam cars produced by twins Francis
E. and Freeland O. Stanley, who had been school teachers in Maine. For several years, the
“Stanley Steamer” was the fastest vehicle on the road. In 1906, the Stanley Rocket set five world
speed records in Daytona Beach, Florida, hitting over 127 miles per hour [9].
The electric car, utilizing rechargeable batteries, was another promising alternative to the
gas-powered vehicle. In 1900, more than one-quarter of the almost 4,200 American automobiles
produced were electric. However, twenty years later the commercial viability of the electrics had
ended. As with the steamers, electric cars had some decided advantages over the motorcar: ease
of operation, no emissions of foul odors and gases, and a quiet ride. Yet as a road vehicle,

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electric cars had a major problem: limited range. At the turn of the twentieth century, they could
only go twenty miles before requiring a recharge [10].
With greater availability of gasoline and oil lubricants after the gigantic Spindle top oil
strike in southeast Texas in 1901, and favorable publicity from automobile race results, the
gasoline-powered car claimed performance superiority over its competitors. In 1900, Ransom E.
Olds switched from producing steam-driven cars to producing gasoline-fueled vehicles, and in
1903, Henry Ford founded a motorcar company specializing in automobiles with internal
combustion engines. When Henry Ford put his mass-produced Model T on the market in 1908,
the car ceased to be a toy for the rich and firmly entrenched the internal-combustion vehicle as
the standard [10].
Over the years, changes in the design, size, weight, and power of automobiles all
contributed to greater gasoline use. The addition of amenities such as air conditioning, power
steering, power brakes, automatic windows, and automatic transmissions reduced fuel economy.
Quality of gasoline (not simply quantity) was crucial to automobile performance [11].
World attention turned to the problem of oil pollution in March 1967, when the
supertanker Torrey Canyon ran aground off the coast of England, spilling most of its 120,000
tons of crude into the sea. In May, President Lyndon Johnson initiated a study of oil pollution
problems, but no major change came in federal offshore policy in the United States. On January
28, 1969, however, Union Oil's Well A-21 blew off the California coast at Santa Barbara. The
hole was capped quickly, but thousands of gallons of oil escaped from a fissure in the ocean floor
[11].
The major battle over oil production during the 1970s, however, was fought not over
water, but land: the Alaska pipeline. Oil exploration was on the rise in the late 1960s after the
world oil glut receded. After an unsuccessful attempt near the Sagvanirktok River, Atlantic
Richfield (ARCO) struck a massive field (estimated at 4.8 billion barrels) at Prudhoe Bay in
1968. Soon there was growing support for the construction of a pipeline to run 800 miles from
Prudhoe Bay south to the Port of Valdez. Environmentalists fought against the pipeline, fearing
that it would destroy precious wilderness areas [11].

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1.3 Classification of Fuels
Engine fuels can be any liquid or gaseous hydrocarbons used for the generation of power in
an internal combustion engine. There are several materials that can be used in the internal
combustion engine as fuel component. These materials are classified as follows:
1. Drive trains which can be Otto engines (gasoline, PB, CNG, ethanol, etc.) or Diesel
engines (diesel gas oils, CNG, diethyl-ether, etc.).
2. Origin which can be Produced from exhaustible energy carriers or Produced from
renewable energy carriers (bio-fuels based on biomass).
3. Number of feedstock resources which can be one resource (e.g., fatty acid methyl esters
from only triglyceride and fatty acid containing feedstock) or Multiple resources (e.g.,
ethanol; from sugar crops, from crops containing starch, lignocelluloses, hydration of
ethylene).
Alternative fuels are those fuels that are other than gasoline or gas oil derived from
petroleum. The main types of motor fuels are shown in Figure 1.1. The choice of fuel to use
depends on the engine design, availability of the energy source, environmental protection issues,
energy policy, safety technology, human biology, the after treated catalytic system, lubricants,
additives, economy, traditions, and so forth.
The fuel industry categorizes the different types of fuels some of them are as follows:
1. Gasoline: A volatile mixture and flammable liquid of hydrocarbons derived from
petroleum fuel and used as automotive fuel for internal combustion engine. Gasoline
contains essentially all classes of hydrocarbons in the C4 to C12range, but is dominated
by aromatic compounds. Generally gasoline contain small amount of additives suitable
for use as a fuel in a spark-ignition internal combustion engine.
2. Diesel fuel (also called diesel oil): combustible liquid used as fuel for diesel engine,
ordinarily obtained from frictions of crude oil that are less volatile than friction used in
gasoline. In diesel engine the fuel is ignited by heat of air compressed in the fuel in
cylinder, with the fuel injected in a spray into hot compressed air. Diesel fuel releases
more energy in combustion on gasoline, so diesel engines generally produce better fuel
economy than gasoline engines.

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3. Racing gasoline: A special automotive gasoline that is typically of lower volatility, has a
narrower boiling range, a higher antiknock index, and is free of significant amounts of
oxygenates. It is designed for use in racing vehicles, which have high compression
engines.
4. Aviation gasoline: A fuel used in an aviation spark-ignition internal combustion engine.
5. Petroleum gases (LPG) Gas phase hydrocarbons, mainly C3 and in low quantity C4.
Their quality is determined by the country or regional standards. Compressed natural gas
(CNG) predominantly methane compressed at high Pressures suitable as fuel in internal
combustion engine.
6. Diesel fuel: A middle distillate from crude oil commonly used in internal combustion
engines where ignition occurs by pressure and not by electric spark.
7. Biodiesel: A fuel based on mono-alkyl esters of long-chain fatty acids derived from
vegetable oils or animal fats. Biodiesel containing diesel gas oil is a blend of mono-alkyl
esters of long chain fatty acids and diesel gas oil from petroleum [12].
Figure 1.1 Main types of motor/engine fuels.

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1.4 Characteristics of fuels
1. Cleanliness: Probably the most necessary characteristic of diesel fuels is cleanliness. Any
foreign material present in diesel fuel will certainly cause damage to the finely machined
injector parts. Any damage to the fuel injectors will cause poor operation or render the
Engine in operative. Controlling dirt and moisture content in diesel fuel is more difficult
because it is heavier than gasoline. This causes foreign material to remain in suspension
longer, so that sediment bowls do not work as well as with gasoline fuel systems.
2. Viscosity: The viscosity of a fluid is an indication of its resistance to flow. What this
means is that a fluid with a high viscosity is heavier than a fluid with a low viscosity. The
viscosity of diesel fuel must be low enough to flow freely at its lowest operational
temperature, yet high enough to provide lubrication to the moving parts of the finely
machined injectors. The fuel must also be sufficiently viscous so that leakage at the pump
plungers and dribbling at the injectors will not occur. Viscosity also will determine the
size of the fuel droplets which, in turn, govern the atomization and penetration qualities
of the fuel injector spray.
3. Volatility: fuels contain variable mixtures of hydrocarbon and additives. The volatility of
the fuel is of extreme importance since the combustion inside the engine occurs when the
fuel is at vapor state. Fuel with low volatility is often associated with liquid fuel being
inducted into the cylinder especially at cold start or at low ambient temperature. The
liquid fuel inducted into the cylinder can be responsible for an increase in HC and CO
emissions and thus poor efficiency. Volatility also influences cold-start fuel economy.
This is because spark-ignition engines start on very rich mixtures and continue to run on
rich mixtures until they reach their normal operating conditions, this is to ensure adequate
vaporization of fuel. Consequently, increasing the volatility of the fuel will decrease the
fuel consumption at cold start, and thus HC emissions.
4. Ignition Quality: The ignition quality of a fuel is its ability to ignite spontaneously under
the conditions existing in the engine cylinder. The spontaneous ignition point of a diesel
fuel is a function of pressure, temperature, and time. Because it is difficult to reproduce
the operating conditions of the fuel artificially outside the engine cylinder, a diesel engine
operating under controlled conditions is used to determine the ignition quality of diesel

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fuel. The yardstick that is used to measure the ignition quality of a diesel fuel is the
Cetane number scale. The Cetane number of a fuel is obtained by comparing it to the
operation of a reference fuel. The reference fuel is a mixture of alpha methylnaphthalene,
which has virtually no spontaneous ignition qualities, and pure Cetane, which has what
are considered to be perfect spontaneous ignition qualities. The percentage of Cetane is
increased gradually in the reference fuel until the fuel matches the spontaneous ignition
qualities of the fuel being tested. The Cetane number then is established for the fuel being
tested based on the percentage of Cetane present in the reference mixture.
5. Multi-fuel Engine Authorized Fuels. Multi-fuel engines are four stroke cycle diesel
engines that will operate satisfactorily on a wide variety of fuels. The fuels are grouped
accordingly: Primary, Alternate I, Alternate II and Emergency Fuels. Primary fuels will
operate the multi-fuel engine with no additives. Alternate II Fuels generally require the
addition of diesel fuel to operate the multi-fuel engine. Emergency fuels will operate the
multi-fuel engine with the addition of diesel fuel; however, extended use of fuels from
this group will cause eventual fouling of fuel injection parts. It should be noted that there
are no adjustments necessary to the engine when changing from one fuel to another.
6. Fuel Density Compensator: multi-fuel engine operates on a variety of fuels, with a broad
range of viscosities and heat values. These variations in the fuels affect engine output.
Because it is unacceptable for the power output of the engine to vary with fuel changes,
the multi-fuel engine is fitted with a device known as a fuel density compensator. The
fuel density compensator is a device that serves to vary the quantity of fuel injected to the
engine by regulating the full load stop of the fuel pump. The characteristics of the fuels
show that their heat values decrease almost inversely proportional to their viscosities. The
fuel density compensator uses viscosity as the indicator for regulating fuel flow. Its
operation is as follows: first, the fuel supply enters the compensator through the fuel
pressure regulator, where the supply pressure is regulated to a constant 20 psi regardless
of engine speed and load range. Second, the pressure regulated fuel then passes through a
series of two orifices. The two orifices, by offering greatly different resistances to flow,
form a system that is sensitive to viscosity changes. The first orifice is annular, formed by
the clearance between the servo piston and its cylinder. This orifice is sensitive to
viscosity. The second orifice is formed by an adjustable needle valve and, unlike the first,

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is not viscosity sensitive. After the fuel passes through the two orifices, it leaves the
compensator through an outlet port. From here, the fuel passes back to the pump. Third,
The higher the viscosity of the fuel, the more trouble it will have passing through the first
orifice. Because of this, the fuel pressure under the servo piston will rise proportionally
with viscosity. Because the second orifice is not viscosity sensitive, the pressure over the
servo piston will remain fairly constant. This will cause a pressure differential that
increases proportionally with viscosity that, in turn, will cause the piston to seek a
position in its bore that becomes higher as viscosity increases. Lastly, the upward
movement of the servo piston will move a wedge-shaped movable plate which will
increase fuel delivery. A lower viscosity fuel will cause the piston to move downward
causing the pump to decrease fuel delivery.
7. Diesel engines have a tendency to produce a knock that is particularly noticeable during
times when the engine is under a light load. This knocking occurs due to a condition
known as ignition delay or ignition lag. When the power stroke begins, the first
molecules of fuel injected into the combustion chamber must first vaporize and superheat
before ignition occurs. During this period, a quantity of unburned fuel builds up in the
combustion chamber. When ignition occurs, the pressure increase causes the built-up fuel
to ignite instantly. This causes a disproportionate increase in pressure, creating a distinct
and audible knock. Increasing the compression ratio of a diesel engine will decrease
ignition lag and the tendency to knock. This contrast with a gasoline engine, whose
tendency to knock will increase with an increase in compression ratio. Knocking in diesel
engines is affected by factors other than compression ratio, such as the type of
combustion chamber, airflow within the chamber, injector nozzle type, air and fuel
temperature, and the Cetane number of the fuel [13].

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Chapter two
Fuel system components
The fuel system includes all necessary auxiliary systems/equipment required to make fuel
available for producing the necessary heat. The equipment required in the fuel system depends
on the type of fuel used. The amount of fuel and air needed for steam generation are
automatically controlled per steam demand. The fuel system is made up of the fuel tank, pump,
filter, and injectors or Carburetor, and is responsible for delivering fuel to the engine as needed.
The main components of fuels system is shown in figure 2.3. Each component must perform
flawlessly to achieve expected vehicle performance and reliability the following components of
this system: fuel tank, fuel filter, fuel pump, fuel tank ventilation system, intake manifold, air
filter, Carburetor, carburetion choke system, and related carburetion components [14].
1. Fuel Tanks: The fuel tank is for storage of fuels in liquid form. There are many different
types and shapes of fuel tanks. Each size and shape is designed for a specific purpose.
The fuel tank must be capable of storing enough fuel to operate the engine for a
reasonable length of time. The tank must be closed to prevent contamination by foreign
objects. It must also be vented to allow air to enter, replacing any fuel demanded by the
engine. Three other tank openings are required--one to fill, one to discharge, and one to
drain. The location of the fuel tank is dependent upon using an area that is protected from
flying debris, shielded from collision damage, and not subject to bottoming of the
vehicle. A fuel tank can be located just about anywhere in the vehicle that meets these
requirements. The most common material for fuel tanks is thin sheet metal coated with
lead tin alloy to prevent corrosion. Because corrosion is a major concern, fibber glass and
a variety of moulded plastics are also widely used in the manufacture of fuel tanks. The
walls of the tank are manufactured with ridges to give strength. Internal baffles are
installed in the tank to prevent the fuel from sloshing and to increase its overall strength.
Some tanks are made with a double wall with a layer of latex rubber in between. The
purpose of the wall is to make the tank self sealing.
Fuel tank contains more elements made together some of them are: Filler Pipe. A
pipe is provided for filling the tank or cell, designed to prevent fuel from being spilled
into the passenger, engine, or cargo compartments. The filler pipes used on military

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vehicles are designed to allow their tanks or cells to be filled at a rate of at least 50
gallons per minute.
Fuel outlet is located approximately 1/2 inch above the bottom of the fuel tank or
cell. This location allows sediment to fall to the bottom of the tank or cell without it being
drawn into the fuel system.
The fuel tank needs a ventilation system to keep the pressure within it equal to
atmospheric pressure. Air must be allowed to enter the tank as the fuel is pumped out.
Without ventilation of the tank, the pressure in the tank would drop to the point where the
fuel pump would not be able to draw fuel from it. In some cases, the higher pressure
around the outside of the tank could cause it to collapse. Also temperature changes cause
the fuel in the tank to expand and contract. Absence of a ventilation system could cause
excessive or insufficient fuel line pressure.
Figure 2.1 Fuel tank
2. Fuel Filters: The fuel filter traps foreign material that may be present in the fuel,
preventing it from entering the carburetor or sensitive fuel injection components. At least
one fuel filter is used in any fuel system. A fuel filter can be located in any accessible
place along the fuel delivery line. Filters also can be located inside fuel tanks,
carburetors, and fuel pumps. Operation. The various types of fuel filters are: Replaceable
Inline Filter which is periodically replaced. The body of the filter acts as a sediment
bowl. Inline Filter Elements (Elements that fit in the carburetor inlet or inside the fuel

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tank on the outlet) are replaceable filters at intervals and contain no sediment bowls.
Glass Bowl Filter with Replaceable Element is sediment bowl must be washed out
whenever the element is replaced. Some fuel pumps have a glass bowl type gas filter built
in. Filter elements are made from ceramic, treated paper, sintered bronze or metal screen.
Figure 2. 2 Fuel filter
3. Fuel Pumps: The fuel pump delivers fuels from the fuel tank to the engine. Early
automotive equipment used gravity to feed fuel to the engine. This is no longer practical
because it limits the location of the fuel tank to positions that are above the engine.
Pumps can be mechanical or electrical. The mechanical type of fuel pump is generally the
more popular pump used for fuel engine applications. It is usually more than adequate
and is much cheaper than an electric pump. The electric pump is more desirable because
of the electric pump will supply fuel to the engine immediately after the ignition key is
turned on. The engine must be tuned by the starter for a mechanical pump to operate. The
electric pump can be mounted away from heat to reduce the possibility of vapor lock.
Mechanical, Positive Type. The positive type mechanical pump operates in the same
manner as the non positive type. The difference is that the diaphragm pull rod is solidly
linked to the rocker arm. The pump, therefore, will not regulate fuel line pressure. When
this type of pump is used, a separate fuel pressure regulation device must be employed
which will bypass excess fuel back to the fuel tank. Mechanical, Non-positive Type This
is currently the most popular configuration of an automotive fuel pump. Electric, Bellows
Type. The bellows type electric fuel pump works in the same manner as the non-positive
type mechanical pump. The difference is that it is driven by an electric solenoid rather
than a mechanical camshaft.

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4. Fuel lines: Fuel lines carry the fuel from the tank to the engine. Fuel lines can be heavy
weight lines for the high pressures found between the injection pump and the injectors,
medium weight lines for the light or medium fuel pressures found between the fuel tank
and injection pump, and lightweight lines where there is little or no pressure. Fuel lines,
which connect all the units of the fuel system, are usually made of rolled steel or,
sometimes, of drawn copper. Steel tubing, when used for fuel lines, is generally rust
proofed by being copper or zinc plated. Fuel lines are placed as far away from exhaust
pipes, mufflers, and manifolds as possible, so that excessive heat will not cause vapor
lock. They are attached to the frame, the engine, and other units in such a way that the
effect of vibration is minimal, and so that they are free of contact with sharp edges which
might cause wear. In areas where there is a lot of movement, as between the car`s frame
and rubber-mounted engine, short lengths of gasoline resistant flexible tubing are used
5. Fuel injectors: Most domestic cars after 1986 and earlier foreign cars came from the
factory with fuel injection. Instead of a carburetor to mix the fuel and air, a computer
controls when the fuel injectors open to let fuel into the engine. This has resulted in lower
emissions and better fuel economy. The fuel injector is basically a tiny electric valve
which opens and closes with an electric signal. By injecting the fuel close to the cylinder
head the fuel stays atomized (in tiny particles) so it will burn better when ignited by the
spark plug. Fuel injectors are arguably the most important fuel system component. The
job of the injectors is to deliver a precise amount of atomized and pressurized fuel into
each cylinder. Highly atomized, pressurized fuel distributed evenly throughout the
cylinder results in increased power and fuel economy, decreased engine noise, and
smoother operation. Fuel injector is an electronic valve that opens/closes at regular
intervals to deliver the right amount of fuel to the engine.
6. Carburetors: The process of preparing an air-fuel mixture away from the cylinders of an
engine is called carburetion and the device in which this process take place is called
carburetor. A carburetor takes the fuel and mixes it with air without computer
intervention. While simple in operation, they tend to need frequent tuning and rebuilding.
This is why newer cars have done away with carburetors in favor of fuel injection. Main
purpose of carburetor is to mix the right amount of air and fuel and deliver it to the
engine.

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Figure 2.3 Main components of fuels system
Fuel system main components are:
1. Container.
2. Recirculation valve.
3. Fuel pressure regulator.
4. Injection valve.
5. Vibration dampers.
6. Ventilation and air release.
7. Fuel runback.
8. Fuel flow.
9. Air release and gravity valve.
10. Fuel tank.
11. Initial fuel pump.
12. Non-return valve.
13. Fuel pump.
14. Fuel filter.

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Chapter Three
3.1 Fuel Additives
In modern automotive fuels, a combination of several chemical additives is used in order
for the fuel to meet the desired performance level. These chemical additives in small dosages
combine to add or improve properties of virgin fuels that cannot be obtained through the refining
processes. The most important are additives that improve the flow of gasoline and diesel oils.
Sometimes the additive is even used to realize better margins by diverting a value-added product
to other applications. Additives are also used in other petroleum products such as heating oil,
aviation fuels, and lubricants in order to improve their performances [15].
Fuel additives have been used in the oil industry since 1925 or 1930. Initially, Cetane
improvers, octane number improvers (tetra-ethyl-lead), dyes, and antioxidants were used to raise
fuel qualities. These were followed by the incorporation of metal deactivators, corrosion
inhibitors, deposit modifiers, and anti-icing agents in 1940s. Diesel stabilizers and lubricity
improvers were introduced in the 1950s. Deposit control additives, diesel flow improvers, and
demulsifies were developed in the 1960s and 1970s. In 1980s, diesel and gasoline detergent
additives and drag reducers for pipelines were introduced. From 1990 onward, many of these
additive chemistries have been improved. In the meantime, anti-valve seat recession additives
and wax dispersants for diesel fuels have been developed.
There are six reasons for using additives in fuels:
1. To improve handling properties and stability of the fuel.
2. To improve combustion properties of the fuel.
3. To reduce emissions from fuel combustion.
4. To provide engine protection and cleanliness.
5. To increase in the economic use of the fuel.
6. To establish or enhance the brand image of the fuel [16].
Conventionally, chemical compounds added in high concentrations (typically >1%) at the
refinery are called blending components, and compounds added in lower concentrations
(typically <1%) at the refineries are called refinery (functional) additives. The even lower
concentrations of chemical compounds added at depots and terminals by companies are called
performance additives. Blending components are mainly refined petroleum streams and

17
oxygenates, whereas functional and performance additives are mainly mixtures of chemical
compounds dissolved in solvents. The concentrations of additives in fuels are not regulated.
Typical concentrations of selected groups of additives for engine gasoline (petrol) are listed in
Table 3.1. The additive concentrations are highly proprietary, and the treat levels will vary to a
large degree depending upon the product, the fuel distributor, the refinery and the type of
additive used. Many manufacturers use additional additives to provide value additions. Diesel
fuels contain another set of additives. Some of these appear similar to the additives, according to
function, used in gasoline, but they may differ in chemical composition and structure. Various
types of markers are also used in diesel fuel, and in kerosene, to indicate their origins.
Descriptions of diesel fuel additives and their suggested approximate dosage are given in Table
3.2. The additive concentration can be varied depending on the mixture’s chemistry and the
chemical compositions of the fuels. But the dosage should be determined experimentally, at the
optimum concentration to meet fuel standards [17].
Gasoline and Diesel fuel used in automotive fuel system have different additives. Gasoline
additives for distribution Systems are Antioxidants, Metal deactivators, Antistatic agents,
Corrosion inhibitors, Sediment reduction agents and Dyes. Gasoline additives for vehicle fuel
system are: Antiknock additive (was tetra ethyl lead, which is now phased out), Anti-valve seat
recession additive (also phased out due to metallurgy change in the engines), Carburetor
detergents (gradually being phased out due to the introduction of injectors), Deposit control
additives, Deposit modifiers, Friction modifiers and Lubricity improvers. Diesel additives for
distribution System are: Antifoam agents, Antistatic agents, Biocides, Corrosion inhibitors,
Sediment reduction agents, Dyes, Demulsifiers, Flow improvers/wax crystal modifiers/wax
dispersants Metal deactivators, Markers to check origin and Stabilizers. Diesel additives for
vehicle fuel System are: Cetane improvers, Combustion improvers, Deposit control additives,
Injector detergents, Lubricity improvers, Friction modifiers [18].
Additives for gasoline and diesel distribution systems are used in refineries to meet
minimum fuel specifications at the optimum cost without compromising on the yield of the
products. For example, diesel fuels of acceptable flow properties can be obtained in the refineries
by reducing the wax content of the fuel. Wax removal, however, is much more costly than the
use of a flow improver that controls or modifies the wax crystals at lower temperatures and also
does not reduce the yield. Additives like antioxidants, metal deactivators, and stabilizers help in

18
maintaining the quality of the fuels during storage and transportation. Thus the additives are used
in the distribution system would be varied according to the need and their treat level. Additives
for the vehicle fuel system are beneficial only when the fuel enters into the intake system of the
engine. Fuel quality standards have undergone a ratcheting-up gradation with progressive
improvements in engine design and more stringent environmental regulations. These changes in
fuel quality have involved reductions in sulfur, aromatics, benzene, poly-aromatics, olefins, and
lead and improvements in octane numbers, Cetane numbers, oxidation stability, and storage
stability. In addition, the fuels are also treated to control deposit formation in the engines. All
these changes, despite the heavy investments and process changes in the refineries cannot be met
by refiners without the use of fuel additives to perform the desirable functions [19].
There are other minor additives used for specific purposes, such as the combustion
catalyst (usually an organometallic compound that lowers the ignition point of fuel in the
combustion chamber reducing the burning temperature from 425–650 °C) and burn rate modifier
(increases the fuel burn time resulting in an approximate 30% increase of the available BTUs
from the fuel).
Table 3. 1 Additives of gasoline fuels and their functions

19
Table 3. 2 Additives of Diesel fuels and their functions

20
3.2 Types of fuel additives
1. Deposit Control Additives (Detergent Dispersants): During combustion all fuels and
engine oils form some deposits in the engine. No degree of refinement and processing of
the fuel and lube oil in the refinery can eliminate the formation of deposits in the engines.
Deposits of soot, sludge, lacquer, and varnish are formed, either due to the incomplete
combustion of fuel or due to the degradation of engine lubricating oil. The burning of fuel
in the presence of air (oxygen and nitrogen) theoretically results to CO2, H2O, and SOx.
Some amount of NOx will also be formed if the temperature is favorable (high enough).
However, ideal combustion is not possible, and some products of decomposition are
formed that are rich in carbon and yet contain hydrogen, oxygen, and sulfur too. These
products are polar in nature and tend to get attracted to each other, forming bigger
aggregates. Deposits in both gasoline and diesel engines and in their fuel systems
adversely affect the operation of the vehicle. Detergent-dispersant additives are blended
in fuels to prevent the formation of different deposits and to clean the fuel system and
combustion chamber for different engines. Their importance is reflected by the fact that
their share is about 40–50% of all additives used. Deposits can form both from fuel and
from the lubrication oil [20].
2. Detergent Additives and Exhaust Emissions: detergent additive have effects on the
quality and quantity of the exhaust gas emission. That is to say, while detergent additives
are effective in reducing the formation of deposits in internal combustion engines, it is
difficult to evaluate the advantage to exhaust emission, as there are many factors that can
affect engine emissions. In other words, detergent additives do not reduce directly the
exhaust gas emissions from vehicles, but rather reduce the deposits that affect engine
performance negatively. Therefore fuels additives reduce emissions lost due to deposit
formation in the engine by keeping the fuel system clean [21].
3. Antiknock Additives (Octane Number Improvers): Gasoline engine knocking is a
combustion phenomenon that takes place when the air-fuel mixture in the gasoline engine
does not burn smoothly or evenly. Knocking in gasoline engines is an undesired acoustic
occurrence when the air and fuel mixture ignites before the upper point of piston in spark
ignition vehicles. Octane is a better measure of how the fuel behaves under a load and it

21
gives information about the combustion/compression tolerance properties of the mixture
in the actual engine. Octane Number Improver Additives An antiknock compound is
added in gasoline to reduce engine knocking by increasing the fuel’s octane rating. The
use of antiknock additives permits greater efficiency and higher power output because of
the higher compression ratios they produce [22].
4. Cetane Number Improver: Cetane is an unbranched open chain Alkane molecule with 16
carbon atoms. Cetane molecule has been assigned a Cetane number of 100, while alpha-
methyl naphthalene has been assigned a Cetane number of 0. The Cetane number is the
index number of the auto ignition property of the diesel fuel and diesel fuel components.
Accordingly, the Cetane number measures how quickly the fuel starts to burn (auto-
ignites) in diesel engines. This is the time period between the start of injection and start
of combustion (ignition) of the fuel. In certain diesel engines, the higher Cetane fuels
have shorter ignition delay period than lower Cetane fuels. Generally, diesel engines run
well with a Cetane number of 40–55. Fuels with higher Cetane numbers that have shorter
ignition delays provide more time for the fuel combustion process to be completed.
Hence higher speed diesels engines operate more effectively with higher Cetane number
fuels. Several different additives have been tried to increase the Cetane number of diesel
fuel. Most Cetane improvers contain alkyl nitrates that readily break down to provide
additional oxygen for better combustion. These also break down and oxidize fuel in
storage [22].
5. Metal Deactivators: Trace amounts of metals like copper or their soluble compounds
accelerate the oxidation of fuels by catalyzing the reaction, thereby forming gums and
deposits at a faster rate. Copper and its alloys are extensively used in the chemical
processing plants and also in the distribution and automotive fuel systems. Whenever
gasoline are treated with phenolic antioxidants, the adverse gum formation effect has
been noticed. This is because the phenolic compounds reduces the divalent copper into a
monovalent copper, which catalyses the oxidation process. When the antioxidant is
depleted in the reduction process, the monovalent copper accelerates the formation of
gums. Thus inhibited gasoline show lower induction time as compared to the uninhibited
product. This problem has been resolved by using a metal deactivator compound, to
passivate the copper metal [21].

22
6. Lubricity Improvers: Lubricity improvers and friction modifiers both work through the
action of film formation on the metal surfaces. However, lubricity improvers are meant
for protecting the fuel pump from wear through the same mechanism of surface
adsorption, since the friction modifiers reduce the friction between moving engine parts.
Lubricity improvers are generally surface active compounds and get concentrated at the
surfaces of separation, forming extremely thin adsorption layers. These thin layers are
capable of producing marked changes in molecular nature and surface characteristics.
This leads to a change in the kinetics of the processes involved in the transfer of
substances across surfaces of separation and in the second place to the changes in the
condition of molecular interaction between the two contacting surfaces. These include
conditions of cohesion, adhesion, friction, and molecular interaction. Thus the addition of
small quantity of a surface active ingredient can generate many changes and control
many technological processes [23].
7. Friction Modifiers: In an engine, about 18% of the fuel’s heat value, which is the amount
of heat released the combustion of the fuel, is lost through internal friction in engine
components, through the bearings, valve train, pistons, rings, water and oil pumps, and
the like. Only about 25% of the fuel’s heat value is converted to useful work at the
crankshaft. Friction occurring at the piston rings and parts of the valve train accounts for
over 50% of the heat value loss. A lubricity-improving fuel additive, such as a friction
modifier, capable of reducing friction at these engine components by one-third preserves
an additional 3% of the fuel’s heat value for useful work at the crankshaft. Therefore
there has been a continual search for friction modifiers that improve the delivery of the
friction modifier to strategic areas of the engine and hence improve the fuel economy of
engines [24].
8. Combustion Improvers: The combustion of the fuels can be enhanced by the use of a
catalyst. These are generally fuel-soluble organic-metal compounds or complexes of iron,
such as Substituted ferrocenes, iron naphthenate, iron succinate, stoichiometric or over-
based iron soaps (carboxylate or sulfonate), iron picrate, or iron carboxylate and iron
beta-diketonate complexes. Iron carboxylate, such as iron tris(2-ethylhexanoate) has been
preferred as a cost-effective source of the fuel-soluble iron. A wide range of “substituted
ferrocenes” are known that can be used as combustion improver catalysts [25].

23
3.3 Additive Compositions
Usually automotive fuel additives are not blended individually to the base fuel; they are
added, except for some additives, as a prepared concentrated solution of additives with an
adequate ratio. This is called the additive composition or additive package. Components of the
fuel additive packages are the following: Active agent (e.g., detergent/dispersant/antioxidant)
and Solvents (e.g., synthetic oils, polyisobuthilenes, polyether, polyether amines) and cosolvents
(e.g., aromatics, alcohols). The packaged solution of additives has to be stable and completely
soluble in fuel [26].

24
CONCLUSION
Automotive fuel system plays a major role in supplying fuel to the engine. If there is no
fuel supply to engine, the vehicle won’t work. Fuel system plays a major role in running a
vehicle. Various types of fuel systems are used in automobiles because fuel systems vary from
engine to another engine. Fuel system contains a variety of parts to store the fuel, supply and
circulate the fuel for an effective way. The major components of the fuel system are the fuel
tank, the fuel and filters, the fuel lines, fuel pumps, etc. If any of the components in the fuel
system fail, the vehicle will have a significant drop in performance, or will even stop working.
We have discussed this fuel system parts one by one in the report.
A vehicle without fuel system, without supply of fuel, you cannot move the vehicle even
an inch. Speed of the vehicle depends on the supply of fuel and the design of the fuel system.
The better supply of fuel is the better would be the combustion of the fuel. Better fuel system
leads to better performance of Automotive. A good fuel supply system should be able to deliver
the fuel correctly at the end of the compression stroke.
Automotive uses fuels to combust and produce chemical energy which is converted into
thermal energy, which is further converted into mechanical work. To increase performance,
efficiency, quality and power of the fuel it is used fuel additives. Fuel additives are combination
of several chemicals. Fuel additives are important because they improve stability of the fuel,
improve combustion properties of the fuel, reduce emissions from fuel combustion, provide
engine protection, cleanliness and increase in the economic use of the fuel.

25
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3. Radler, M., Bell, L. (2010). US energy demand set for slim expansion in 2010, Oil Gas J.,
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fuel sources. 20th World Petroleum Congress, December, Doha Quatar.
5. Szalkowska, U. (2009). Fuel quality—global overview. Proceedings of 7th International
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26
16. Russell, T. J., Batt, R. J., Mulqueen, S. M. (2001). The effect of diesel fuel additives on
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containing a mannich condensation product a poly (oxyalkylene) monool, and a
carboxylic acid. US Patent 6,511,519, January 28.

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