Ignition Fuel Pump and Spark Plug

8/12/2019 Ignition Fuel Pump and Spark Plug

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IGNITION SYSTEM-SI ENGINE

the ultimate spark creator in petrol

engine.

UNIT-2

EME-505 I.C.ENGINES

B.TECH 5TH SEM MECHANICAL ENGINEERING

2011 batchBY

VINOD KUMAR YADAV

MECHANICAL ENGG. DEPTT

G.L.B.I.T.M


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BASICS OF IGNITION SYSTEM

SI enginelow compression ratio and high self ignition temperatureof fuelso for combustion ignition source is must.

Principle:A conventional ignition system should provide sufficientlylarge voltage across the spark plug electrodes to affect the sparkdischarge.

Air is poor conductor of electricity- an air gap in an electric circuitacts as a high resistance. But when a high voltage is applied acrossthe electrodes of a spark plug, it produces a spark across the gap.

When such a spark is produced to ignite a homogeneous A/Fmixture in the combustion chamber of an engine it is called thespark ignition engine (or SI Engine).


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BASIC REQUIREMENT OF IDEAL IGNITION SYSTEM

Supply necessary energy within a small volume in a time sufficiently

short to ensure that minimum energy is lost other than that neededto establish the flame under all conditions of operation.

For A/F range 12-13:1 a spark under 10 millijoules is sufficient to

initiate the combustion.

The system must produce and distribute high voltage of the order of

20000 volts to 22000 volts for generating spark between theelectrode gap

The system must have a source of electrical energy (may be a

battery or a generator or a magneto).

Battery voltage is usually 6 to 12 volts. This low voltage is boosted

by means of an induction coil, contact breaker and a condenser to avalue sufficient to meet the breakdown voltage and to release

sufficient energy for spark generation.


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TYPES OF IGNITION SYSTEM

1. Battery Ignition system(conventional and transistor assisted)

2. Magneto ignition system

3. Electronic ignition system


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BASICS OF BATTERY IGNITION SYSTEM

Distributor form the secondary circuit

COMPONENTS OF THE IGNITION SYSTEM


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1- A Ballast resistor: In series with primary winding to regulate

primary current. The objective of BR is to prevent injury to the sparkcoil by overheating if the engine should be operated for a long time

at low speed, or stalled with breaker in closed position.

This coil is made of iron wire, and iron has the property that its

electrical resistance increases very rapidly if a certaintemperature is exceeded.

The coil is therefore made of wire of such size that if the

primary current flows nearly continuously, the ballast coil

reaches a temperature above that where this rapid increase in

resistance occurs. This additional resistance in primary circuit

holds the primary current down to safe value.

For starting this resistor is by passed so that more current can

flow in the primary circuit.

COMPONENTS OF THE IGNITION SYSTEM


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2-A cam rotating at camshaft speed operates the contact

breaker points and causes them to open and close.

3- Ignition coil to step up the 6 volts or 12 volts of the

battery to a high tension voltage sufficient to promote

and electric spark across the electrodes of the spark

plug.

4- A distributor to distribute the high voltage to different

spark plugs at correct time

5- A battery : 6 volts or 12 volts (Lead acid light duty

commercial vehicles : Alkaline battery heavy dutycommercial vehicles)

6- Contact breaker points (CB point) : Made of hard

material (tungsten) with 3 mm diameter.

COMPONENTS OF BATTTERY IGNITION SYSTEM


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CONSTRUCTION OF IGNITION COIL


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IGNITION COIL CONSTRUCTIONAL DETAILS

The Ignition coil consist of two insulated conducting coil-

primary and secondary.

The primary winding is connected to the battery through an

ignition switch and the contact breaker.

The secondary winding is connected to the spark plugs

through the distributor

In order to boost the voltage the primary windings has a few

hundred turns (100-300) of relatively thick wire (20 gauge)

while the secondary windings contain several thousand turns

(20000-22000) of thin wire (38-40 gauge enameled copper wire

sufficiently insulated to withstand high voltage). More heat is

generated in primary than secondary and so primary windingis wounded over secondary to dissipate heat.

The two wires are also interconnected allowing the secondary

windings to be earthed through the primary circuit


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Ignition coil contd.


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WORKING OF BATTERY IGNITION SYSTEM

When ignition switch closed (switch on) primary winding is

connected to positive terminal post of storage battery. If

primary circuit is closed through the CB point, a current flows

which is called primary current

Primary current produces a magnetic field in core.

A cam driven CB opening mechanism opens it when spark is

required

When CB points are open, the current which had been flowing

now flows into the condenser.

As the condenser becomes charged, the primary current falls

and magnetic field collapses.

The collapse of the field induces a voltage in the primarywinding, which charge the condenser to a voltage much higher

than the battery voltage.

The condenser then discharges into the battery, reversing the

direction of both the primary current and the magnetic field.


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WORKING OF BATTERY IGNITION SYSTEM

The rapid collapse and reversal of the magnetic field in the core

induce a very high voltage in the secondary winding.

The secondary winding consists of large number of turns of

very fine wire wound on the same core with the primary.

The high secondary voltage is led to the proper spark plug by

means of rotating switch (distributor).


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2-MAGNETO IGNITION SYSTEM


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2-MAGNETO IGNITION SYSTEM WORKING

Magneto- special type of electric generator

It is mounted on the engine and replaces all the components

of the coil ignition system except the spark plug and cb point

- A magneto when rotated by the engine, is capable of

producing very high voltage and does not need a battery

as a source of external energy

- The high tension magneto incorporates in itselfwindings to generate as well as to step up the voltage

and thus does not require a separate coil to boost up

the voltage required to generate the spark.

- Magneto can be rotating armature type or rotating

magneto type- The operation of the magneto ignition system is exactly

same as that of the battery coil ignition system. In MIS

as the breaker points are opened and closed with the

help of a cam, the primary circuit flux is charged and

a high voltage is produced in the secondary

circuit


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Magneto Vs Battery Ignition systemS.No Battery Ignition system Magneto Ignition system

1 Requires battery: Difficult to

start the engine when battery is

discharged

No battery, no discharge

2 More maintenance problems

due to battery

Less maintenance

3 Current for primary circuit isobtained from battery

Current is generated by magneto

4 A good spark is available at spark

plug even at low engine speed.

During starting quality of spark is

poor due to low speed.

5 Efficiency of system decreases

with reduction in spark intensity

as engine speed rises.

Efficiency of system increases with

increase in engine speed due to

high intensity spark

6 Occupies more space Occupies less space

7 Used in cars and LCVs Used in Racing cars and two

wheelers


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LIMITATIONS OF BREAKER SYSTEMS

AND NEED OF MODERN IGNITION

SYSTEMS Contact Breaker systems: Available voltage decreases

as engine speed increases due to limitations in current

switching capability of the breaker system and the

decreasing time available to build up the stored energy

in the primary coil.

Due to high current load, the breaker points are

subjected to electrical wear in addition to

mechanical wear which requires frequent

maintenance

So there is a need to develop advanced (Modern)

ignition systems (like TCI and CDI)


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TRANSISTORISED IGNITION SYSTEM

OR

TRANSISTOR ASSISTED CONTACT SYSTEM (TAC)


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The inherent property of transistor is to interrupt a relatively high current

carrying circuit, i.e its ability to control a much larger current in the collector

circuit with a small current in the base circuit, makes it ideal replacement forthe breaker points and condenser of a conventional ignition system.

The emitter (E) of the transistor is connected to the ignition coil through a

ballast resistor and the collector (C) to the battery. When the cam operated

contact point opens the base current and , thereby, the primary circuit current

is interrupted and the normal induction coil operation follows.

The current through the contact breaker is reduced by a large amount due tothe fact that the contact breaker has to switch only the base current



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disadvantages

Source impedance: Opposition exhibited by output terminals to an AC of a

particular frequency as a result of resistance, inductance and capacitance


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4-HIGH VOLTAGE CAPACITIVE DISCHARGE IGNITION

OR

CAPACITIVE DISCHARGE IGNITION (CDI)

In CDI ignition system, a capacitor is used as a means of energy storage. It

is charged to a high voltage (about 500volts) by means of a transformer and

at the moment of ignition, discharged by the thyristor through the primary

circuit which generates a high voltage pulse in the secondary circuit to fire

the spark plug

CDI Trigger box contains Capacitor, thyristor power switch (SCR), charging

device (to Convert battery voltage to the charging voltage of 300 to 500 V by

means of pulse Via a voltage transformer


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Further explanation onTransistorized

Ignition System


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Transistorized Ignition System In automotive applications, the transistor ized

coi l ign i tion sys tems which prov ide a higheroutpu t vo l tage and use electronic triggering tomaintain the required timing are fast replacing theconventional ignition systems. These systems are

also cal led high energy electronic igni t ionsys tems.These have the following advantages:-

1. Reduced ignition system maintenance

2. Reduced wear of the components.

3. Increased reliability4. Extended spark plug life

5. Improved ignition of lean mixtures


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An ignition system using a transistor as a power switch; available as

breaker-triggered TI with contact breaker or as breakerless TI with

magnetic pick-up or hall generator.

This type of maintenance-free electronic ignition system constantly

feeds electrical power to the high tension coil(s) [also known as ignition

coil(s)]. The circuit is switched on and off by a transistor circuit in the

ECU or igniter assembly. This system is commonly found on

motorcycles using fuel injection. The longer spark duration, a feature of

this system, makes it a good choice for improving the fuel combustion

and thereby lowering the exhaust gas emissions.


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CDI SYSTEM WORKING

Capacitor discharge ignition (CDI) or thyristor ignition is atype of automotive electronic ignition system which is widelyused in motorcycles, lawn mowers, chain saws, small engines,turbine powered aircraft, and some cars.

It was originally developed to overcome the long chargingtimes associated with high inductance coils used in inductiveignition systems, making the ignition system more suitable forhigh engine speeds (for small engines, racing engines androtary piston engines).

Capacitor discharge ignition uses capacitor discharge currentoutput to fire the spark plugs.


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ADVANTAGES OF CDI SYSTEM OVER TCI SYSTEM


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Further explanation on

C.D.I.

(Capacitive Discharge

Ignition System)


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Capacito r dis charge ign i t ion (CDI)or thyr istor igni t ionisa type of automotive electronic ignition system which iswidely used in motorc ycles, lawn mowers, chain saws,smal lengines, turb ine powered aircraft, and some cars.It was original ly developed to overcome the longchargingt imesassociated with high inductance coils used

in inductive ignition systems, making the igni t ion sys temmore sui table for high eng ine speeds(for small engines,racing engines and rotary piston engines). Capacitordischarge ignition uses capacitor discharge current output tofire the spark plugs.

C.D.I.

(Capacitive Discharge Ignition

System)
http://en.wikipedia.org/wiki/File:Capacitor_Discharge_Ignition_1.jpghttp://en.wikipedia.org/wiki/File:Capacitor_Discharge_Ignition_1.jpghttp://en.wikipedia.org/wiki/File:Capacitor_Discharge_Ignition_1.jpg


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Electronic capaci tor disc harge igni t ion (CDI) systems

have been common on large industrial engines because the

techn ology has beenin use sin ce the 1960's. An advantage of the capacitor discharge ignition system is

that the energy storage and the voltage step up'

funct ions are accompl ished by separate circui t

e lementsallowing each oneto be op t imised for i ts job.


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Capacit ive discharge ign it ionsystems work b y stor ing energy in anexternal capacito r, which is then discharged into the igni t ion coi lpr imary winding when required. This rate of discharge is much higherthan that found in inductive systems, and causes a correspondingincrease in the rate of voltage rise in the secondary coil winding.

This faster voltage r ise in the second ary wind ing creates a sparkthat can al low combust ion in an enginethat has excess oi lor an overr ich fuel air mixtu rein the combustion chamber. The high ini t ia l sparkvoltage avoids leakage across the spark plug insulator andelectrodescaused by fouling, but leaves much less energy avai lable

for a suff ic ient ly long spark durat ion; this may not be sufficient forcomplete combust ion in a leanburn turbocharged engine resultingin misfiring and high exhaust emissions.

Igni t ion in lean fuel mixtures by capacitor disch arge systems cansometimes only be accompl ished by the use of mult i -spark ignit ion,

where the ignition system duplicates the prolonged spark of inductivespark systems by sparking a number of times during the cycle. This addsgreater stress onto the high-tension leads and can cause considerablespark plug wear and possible failure.


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Basic principle Most ign i t ion sy stemsused in cars are induct ive igni t ion systems,

which are solely relying on the electric inductance at the coil to produce

high-voltage electricity to the spark plugs as the magnetic field breaksdown when the current to the primary coil winding is disconnected(disruptive discharge). In a CDI system, a charg ing circu i tcharges ahigh voltage capacitor, and dur ing the igni t ion point the systemstop s charging the capacitor, allowing the capacitor to discharge itsoutput to the ignition coil before reaching the spark plug.

A typical CDI modu le consis ts of a smal l transformer, a chargingc i rcu i t, a t r igger ing circui t and a main capacitor. First, the systemvoltage is raised up to 400-600 Vby a transformer inside the CDImodule. Then, the electr ic current f low s to the charging circ ui tandcharges the capacitor. The rect if ier insid e the charging c ircui tprevents capacitor discharge before the ignit ion po int. When thet r igger ing c ircui t receives tr igger ing sign als, the t r igger ing circui tstop s the operat ion of the charging circu i t, allowing the capacitorto discharge its ou tput rapidly to the low inductance ignition coil,which inc rease the 400-600 Vcapacitor discharge to up to 40 kV atthe secondary w indingat the spark plug. When there's no triggeringsignal, the charging circuit is re-connected to charge back the capacitor.

M t CDI d l ll f t t


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AC-CDI - The AC-CDImodule obtains its electr ic i ty sourcesolelyfrom the alternat ing currentproduced by th e alternator. The AC-CDI

system is the most basic CDI system which is widely used in smal lengines.

Note that not all small engine ignit ion systems are CDI. Some olderengines use magneto ignition. The entire ignition system, coil and points,are under the magnetized flywheel.

If the engine was rotated while examining the wave-form output of thecoil with an oscilloscope, it would appear to be AC. But you mustconsider that since the charge-time of the coil corresponds to much lessthan a full revolution of the crank, the coil really 'sees' only DC current forcharging the external ignition coil.

There exist some electronic ignition systems that are not CDI. Somesystems use a transistor to switch the charging current to the coil off andon at the appropriate times. This eliminated the problem of burned andworn points, and provided a hotter spark because of the faster voltagerise and collapse time in the ignition coil.

Most CDI modules are generally of two types:


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DC-CDI - The DC-CDI module is powered by the battery, andtherefore an additional DC/AC inverter circuit is included in the CDImodule to raise the 12 V DC to 400-600 V DC, making the CDI

module slightly larger. However, vehicles that use DC-CDI systems

have more precise ignition timing and the engine can be started

more easily when cold.


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Advantages and Disadvantages of CDI

A CDI sy stemhas a shor t charg ing t ime, a fast vol tager ise (between 3 ~ 10 kV/s) compared to typicalinduct ive sys tems (300 ~ 500 V/s) and a shor t sparkdurat ion limited to about 50-80 s. The fast vol tage risemakes CDI sys tems insensi t ive to shunt resistance, butthe l imi ted spark du rat ion can for some applications betoo short to p rovide rel iable igni t ion. The insensitivity toshunt resistance and the ability to fire multiple sparks canprovide improved cold starting ability.

VACUUM ADVANCE


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VACUUM ADVANCE

The vacuum adavnce on spark timing is necessary because the lean mixtures require an

earlier spark timing than the rich mixtures. Therefore as the throttle is closed the spark

must be advanced for optimum performance


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Vacuum advance

When an engine is at idle, it experiences high manifold

vacuum. If you have ever popped a vacuum line off of an

idling automobile engine, then you have heard the loud

hissthat results. That is manifold vacuum suction. Because

the fuel is traveling so slowly and the engine is under

no load, the vacuumin the engine operatesthe advanceon the distr ibuto r, which then advances the timing so the

engine idles smoothly and the spark is happening at the

correct time. When the accelerator is depressed hard or

when the vehicle is under a good load, there is essentiallyzero manifold vacuum. Therefore, the advance mechanism

on the distributor is not actuated at all, resulting in no timing

advance.


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VACUUM ADVANCE


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Vacuum advance mechanism

Vehic les equipped with vacuum advanced distributors (usually older

models) have a "pod" on the side of the distributor, with a rubber hose

attached to it. The hose connects directly to the intake manifold of the

engine so that it receives the full vacuum, or lack there of.

At id le,

when themanifo ld vacuum is high

, the tube attached to theadvance pod wil l suck in, causing the distr ibu tor to advance the

t iming. There are spr ings ins ide the dis t r ibutor which hold the

t iming mechanism in place. They remain in that posit ion until the

manifold vacuum affects them.

Newer automobi les sometimes use a centr i fugal sys tem that uses

weights ins tead of vacuum. The problem with them is that they are

based only on engine RPM(revolutions per minute) and cannot d etect

whether or no t the engine is under a load or no t. Because of that, the

vacuum advanced systems are much more efficient at advancing or

retarding the timing to the engine's needs.

CENTRIFUGAL SPARK ADVANCE


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CENTRIFUGAL SPARK ADVANCE


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centrifugal advance mechanism

The centr i fugal advance mechanism advances the ignition

spark as engine speed increases. This is accom pl ished by

twoweights attached to the cam. As the engine's sp eedand

that of the distr ibuto r shaft increase, the weights move

outw ard by centr i fugal force, thereby turning the cam andcausing th e igni t ion to advance.


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CENTRIFUGAL ADVANCE


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CENTRIFUGAL ADVANCE CONTD..

As speed increases, centrifugal force on the weights movesthem outwards against spring tension.

This movement causes the distributor cam or trigger wheelto move ahead. With this design, the higher the engine speed,the faster the distributor shaft turns, thefarther out the advance weights move, and the farther

ahead the cam or trigger wheel is moved forward or advanced.At a preset engine speed, the lever strikes a stop andcentrifugal advance reaches maximum.

The action of the centrifugal advance causes the contact points

to open sooner, or the trigger wheel and pickup coil turn offthe ECU sooner. This causes the ignition coil to fire with theengine pistons not as far up in the cylinders.


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COMPUTERIZED

ADVANCE

COMPUTERIZED ADVANCE


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COMPUTERIZED ADVANCE The computer ized advance, also known as an electronic spark

advance system, uses various engine sensors and a computer tocontrol ignition timing. The engine senso rs check variousoperat ingcondi t ionsand sends electr ical data to the com puter

The computer an change ignition timing for maximum engine efficiency.Ignition system engine sensors include the following:-

1. ENGINE SPEED SENSOR (reports engine speed to the computer)2. CRANKSHAFT POSITION SENSOR (reports piston position)

3. THROTTLE POSITION SWITCH (notes the position of the throttle)

4. INLET AIR TEMPERATURE SENSOR(checks the temperature ofthe air entering the engine)

5. ENGINE COOLANT TEMPERATURE SENSOR (measures theoperating temperature of the engine)

6. DETONATION SENSOR (allows the computer to retard timing whenthe engine knocks or pings)

7. INTAKE VACUUM SENSOR (measures engine vacuum, an indicator ofload) The computer receives different current or voltage levels (inputsignals) from these sensors.

It i d t dj i i i ti i b d i d i i


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It is programmed to adjust igni t iontiming based on engine condi t ions.The com pu ter may be moun ted on the air cleaner, under the dash, ona fender panel, or under a seat. The following is an example of theoperation of a computerized advance. A vehic le is travel ing down theroad at 50 mph ; the speed sensor detects moderate engine

speed.

The thrott le posit ion sensor detectspart thro tt le and the air inlet andcoo lant temperature sensors report normal operat ing temperatures.The in take vacuum sensor sends high vacuum signals to thecomputer. The com puter receivesall the dataand calculatesthat the

engine requires maximum spark advance. The t iming would occurseveral degrees befo re TDCon the compress ion stroke. This act ionassuresthat high fuel economyis attained on the road.

Ifthe operator began to p ass another vehic le, in take vacuum sensordetects a vacuum drop to near zero and a signal is sent to the

computer. The thrott le posit ion sensor detects a wide, open throt t leand other sensor outputs say the same.

The com puter receives and calculates the data, then, if required,retards ign it ion t iming to prevent spark knoc k.


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Mechanical

Fuel Pump

Mechanical Fuel Pump


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Mechanical Fuel Pump A mechanical fuel pumpis a device that del ivers fuel to the engine.

Due to the fact that mechanical fuel pumps generally work best on

carbu reted engines, they are typically found only on older vehicles. Acarburetor squats over the engine on many older cars and delivers fuel

into the combustion chambers via intake ports. Some older cars ran

the fuel lines below the gas tank so that gravity does the work of

carrying gasoline from the tank to the carburetor. However, many older

models needed a little additional help to get the fuel from the tank tothe carburetor. The mechanical fuel pump, which was usually located

on the side of the engine, was therefore designed to run off of the

enginesmomentum and provide the carburetor with a steady supply of

fuel.


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FIGUREA mechanical fuel pump.


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A mechanical fuel pumpmounts to the side of the engine. A leverorpush ro d on the pump passes through an opening in the side oftheengine and l ines up w ith a special lobe on th e camshaft. As thecamshaft turns, the lobe moves the lever up and down, raising and

lowering a flexible diaphragm inside the pump. With the mot ion of thediaphragm, gasol ine is drawn down the fuel l ines and into thepump. From there, the gasoline is pushed into the carburetor, whichuses the vacuum of the engine to pull fuel into the combustionchambers.

Because diaphragm fuel pumps run d irect ly

off of the engine, they will only work when

the engin e is runn ingor being started. This

prevents dangerous bui ldups of fuel f rom

occurr ing in the l ines. Mechanical fuel pumps

also do not pressur ize the system veryhighly:-

Most carbureted fuel systems run as low as 4

pounds per square inch (psi), and rarely ever

more than 15 psi.

S f f
http://en.wikipedia.org/wiki/File:Fuelpump1.jpg


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Since diaphragm fuel pumps are located r ight on the side of theengine, replacing this part is relatively easy and qu ick. However,despite the low pressure levels of carbureted fu elsystems, if youdisco nnect the l ine that feeds into a mechanical fuel pump, i t wi l ldr ip fuel. The fuel l ine is below th e gas tank, sogravi ty willcont inuously pul l fue l down the l ine if you do not plug it. You willalso need to be sure that you correctly line the lever or push rod upwith the enginescamshaft when installing the new fuel pump, so thatyou do not inadvertently damage the pump when you turn the engineover.

Eventually electronic fuel injection systems, which were favored forgreater accuracy and cont ro l, replaced carburetors. When thishappened, cars also began to require fuel systems that ran underhigh pressure, generally between 40 and 60 psi. Because amechanical fuel pump cannot su ppor t a system under that muchpressure, they were eventually cast aside in favor of the higher

performing electronic fuel pump.

Decline of mechanical pumps


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Decline of mechanical pumps As engines moved away from carburetors and towards fuel

in ject ion, mechanical fuel pumpswere replaced with electr ic fuelpumps, because fuel injection systems operate more eff ic iently at

higher fuel pressures (40-60psi) than mechanical pumps cangenerate. Electr ic fu el pumps are general ly located in the fuel tank,in order to use the fuel in the tank to cool the pum p and to ensu reasteady supp ly of fuel.

Another benefit of an in-tank moun ted fuel pump is that a suc t ion

pumpat the engine could su ck in air througha (difficult to diagnose)faul ty hose connect ion, while a leaking connect ion in a pressurel ine wil l show itsel f immediately. A potential hazard of a tank-mounted fuel pump is that all of the fuel lines are under high pressure,from the tank to the engine. Any leak w il l be easily detected, but isalso hazardous .

Electr ic fuel pum pswill run w henever they are sw itched on, whichcan lead to extremely dangerous situat ions if there is a leak du e tomechanical faultor an accident. Mechanical fuel pum ps are muchsafer, due to their lower operat ing p ressuresand because they 'turnoff' when the engine stops running.


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WARNING:A leaky fuel pum p is dangerous because thefuel may ignite and s tart a f ire!

Another way to check the pump is to disconnect the fuelline at the carburetor and place the end of the line into acontainer. Crank the engine to see if the pump is pushingany fuel through the line. Strong steady spurts of fuelmean the pump is working. No fuel or a weak streammeans a bad pump, a plugged fuel filter, fuel line

blockage or no fuel in the tank.

WARNING:Do not smoke near gasol ine, and do not al lowany sparks near the carbu retor o r open fuel l ine as this

may igni te the fuel causing a f i re! Do no t spi l l gasol ine ona hot engine. Wait un t i l the eng ine has co oled to work onthe fuel system . A lso, avoid sk in contact with gasol ineand do not b reathe the vapo rs.


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Electronic

Fuel Pump


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The fuel pump is a subm ers ib le pumpwith a permanent magnet electr icmoto r. Fuel enters the pump inlet tube

after passing through a sock style filter

and is pushed through the pump by the

motor to the outlet.

Electronic Fuel Pump

It cons is ts of a motor, a vane rol ler pump, a fuel damper,

and a rel ief valve to prevent system damage from overpressure. The fuel pump shares its mounting cage with the fuel

gauge sending unit.
http://www.bombayharbor.com/productImage/0541578001259997016/Electric_Fuel_Pump.JPG


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Long t ime back when the diesel


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Long t ime backwhen the dieselengines had not much evolvedlike today, to extract bestper formance and long l i fe

adequate fuel pressure in thel ines was necessary for dieselpump& nozzlesto workat theiropt imum. Over a per iod oft ime, the pump used to getweak leading to drop in fuelpressure in lines and laboriousworking of the engine. Thisused to resul t in fue l pumpcal ibrat ion that was a cost lyaffair.

FIGURE A typical fuel pump model assembly, which

includes the pickup strainer and fuel pump, as well as the

fuel-pressure sensor and fuel level sensing unit.

T t i f


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To ensure opt imum per formance,additional electr ic fuelpump, either inthe tank or near diesel fi l ter intakeused to be instal led; not in all but in

some where the owners wereknowledgeable or the mechanicsuggested so. In addition to maintainingproper fuel pressure, one problem thatwas the bane of all diesel owners wasof air interlock that was due to, no fuel,

damaged fuel line, frayed 'o' ring of thefilters etc., that resulted in stalling,misfiring etc. Electric fuel pumpremoved the air interlock problem.

FIGURE A roller cell-type electric fuel pump.

SPARK PLUG CONSTRUCTION


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SPARK PLUG HEAT RANGE


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SPARK PLUG OPERATING TEMPERATURE

Documents

Ignition Fuel Pump and Spark Plug