fuel injection

ECU electronic control unit.

the ecu ( electronic control unit) is the brains of the car as it controlls the eletricals of boat or vehical. it is used to controll the fuel injectors, sensors, pumps etc. there are sevral sensors on the engin such as o2 sensor, tpr ( throthle positon switch) , air temp sensor,  mass air flow sensor, map sensor. the readings that the ecu gets from these sensors helps the ecu to make changes to the engin so it runs to how it was programed. for example if the o2 sensor is picking up to much oxogen it will send that messge to the ecu, the ecu will then adjust the air fuel ratio in the intake system to make sure the engin is running more efficantly. ecu's are not cheap and can cost anywere from 2grand and up. also when putting a new ecu in it has to be programed right as miss calculations can resault in  lack of power or a out of time engin.

MASS AIR FLOW SENSOR

a mass air flow sensor measures the amount of air flow into the engin. the sensor is mounted  in between the air cleaner system. the point of having a mass air flow sensor is so that the ecu can record how much air is being sucked into the throtle body so it knows how much air  there is for the combustion process.

AIR TEMP SENSOR

 a air temp sensor is used on a fuel injection system. the sensor is used to help the computer to calculate the density of the air. so when the air heats up the air becomes less dens there for making the computer pump less fuel through the injecters. without an air temp sensor or a faulty sensor it can be telling the ecu the wrong thing making the ecu pump either to much fuel or not enogh fuel through the injectors.

TPS (THROTLE POSITION SENSOR)

 a tps runs off the ecu to the throtle shaft on the throtle body. its tells the ecu how far the throthle (butterfly valve) is open so that the messurment of air  that is flowing into the intake manaflod can help with the amount of fuel the ecu signals to pump into the injecters. a broken or faulty tps can resault in a shutter or jumpy idle and can have bursts of fuel into the boar because the tps has said that the throtle was wide open so a larger amount of fuel was needed there for flooding the engin, reducing power.

refrences for carb project

http://www.motorera.com/dictionary/em.htm

http://www.cdxetextbook.com

http://www.ehow.com

http://www.differencebetween.com

http://www.vw-resource.com

http://www.holley.com

part 3 carb project

if a car or boat is lacking power it could be alot of things but mostly fuel or air, starving the car of air or fuel can slow down the cycle as theres no ignition to  to spark in the boar to creat power. first off ensure  that air is getting into the carb and there is no blockage. check that there is fuel in the fas tank, that its flowing freely through the lift pump and fuel filter. then check that the jet is sprayinng fuel by turning the car over and looking down the barrel of the carb while reving the enging with the throtle. ensureing that fuel and air is getting into the boar is a good place to start. checking the spark plugs to see what kind of condition they are in can help because it can show if theres to much fuel, water , oily  etc.  

to adjust a float in a carb you need to remove the carb from the engin and remove the float bowl.  turn upside down so the float is resting on the needle valve. messure form the top of the bowl to the bottem of the float. should be 16mm ( or to specs in a spec book for that spicific engin) if its not , slightly bend the float with plyers to the correct length. doing this adjust the amount of fuel aloud in the float bowl.

the pupose of a powere valve in a carb is to spray out more fuel when the throtle is wide open. spraying more fuel helps out the jet  and makes the engin go faster, with out the power valve acceleration would be hard to do.

high fuel connsumption can be caused from a heavy foot or having the throtle wide open, but also can be caused by  over sized jets.running rich  or a stuck power valve. having to much fuel in the sytem can flood it and will be a pig to start and run. adjusting the  the idle to lower the fuel mixture can be done with a flat head screw driver usauly turning left or right to turn down or raise the idle speed. idle revs should be any were between 500 and 1000 rpm. anything more will be wasting fuel and putting strain on the engin.

part 2 carb project

when dismatiling a carb there are a few things to be carefull of. when dismatiling a a carb keep it up right or how it would normaly sit when it is atached to the moter. when unbolting the car becarefull of small ball barrings, sprinds slides as they have a spicific place to be. also being carfull while pulling apart a carb helps you rember were certain parts go and how they work. a good note while dismatiling acarb is to take photos and notes so its easy to put back together with no hassels or stress.

on a automatic choke system there is a bimetallic spring that helps with cold starting.when the engin is cold the sping holds the butterfly valve closed, as the engin heats up it slowly opens the valve producing a progressivly leaner fuel mixture. At the same time the high idle gradulay drops back to normal, when the engin is warm the butterfly valve will be fully open, ( standing up) producing the right mixture of air and fuel for the warm engin.

The flow of air from the air filter is drawn in by atmospheric pressure, as it enters the carb the center of the carb gets narow in a smoth,rounded way, this narowness is called the venturi. this creates more of a pull there for sucking more air into the carb, it also helps draw  fuel out of the jet witch mixes with the air.

carb project

  A carb works by mixing fuel and air together for a internal combustion that takes place in the boar to pump the pistons. The carb works by sucking in air through the choke valve in to the Ventura which helps speed up the flow. Fuel is then added to the air by the jet, it sprays the fuel into the passing air which is then sucked trough the throttle end and flows into the boar via the valves.  The amount of air and fuel that goes into the boar is controlled by the throttle valve that opens and shuts according to how throttle you pull

difrent parts of a carb help with the process of mixing fuel and air for the combustion process. in the diagram beside it shows the flow of  clean air entering the carb via the choke plate or butterfly valve.the air is then sucked through a ventura  due to atmosperic pressure casue by the draw back off the piston.the fuel is sprayed out by a fuel jet, there are sevral types of jets eg a idle jet and running jet. the float chamber holds the fuel at atmospheric pressure ready forr mixing or use.the amount of fuel is controlled by the float driven valve wich is controlled by the float, the float drops as fuel leaves the float bowl wich opens the inlet valve for more fuel to be pumped in , the float rise up and shuts off the valve so the carb dose not flood.the oxogen and fuel mixture then travels through the carb to the throtle plate wich controlls how much of the mixture goes into the boar, the throtle valve is controlled by the throtle leaver on the boat  opening alowwing more mixture to go faster and shuting off to slow down reducing the amount of  fuel and air entering the boar.

an emulsion tube  has sevral small holes in wich it air is introduced to the mixture  to atomize and correct  excessive richness at high speeds. the emulsion tube also helps improve idle response and stability when the engin is hot and prevents fuel precolation and genral hot starting problems.

A manual choke is used manually and has to be shut off and put on by the operater. the manual choke closes the choke plate of butterfly valve alowing only a small amount of air into the carb for a more richer mixture to start a cold engin. A automatic choke is one that the engins computer can shut off and turn on by sensing the tempreture of the engine. The point in having a choke is so the car can start easyer  as it alos less air flow and more fuel to be pumped into the boar .a manual choke is located at the front of the carb and can be turned off and on from the car or a switch attached to the choke leaver.

a lift pump is used to raise the level of fluid such as gas or desil into the fuel ines (dose not force it thorugh)   the fuel lines  from the tank. it works by building pressure in the gas tank drawing fuel into the fuel lines .vacum fuel pumps for a two stroke work on a low presure system  drawing the fuel through the fuel lines. Average pressure created by these pumps is anywere between  3-5 psi.

the difrences between diesel and petrol?

diesel is more efficiant and powerfull than petrol due to the hydocarbons with long carbon chains. although diesel is more efficant it puts off alot of  polution and gasses than petrol.in most countries desil is cheaper to buy than petrol. both diesel and petrol are made from crude oil pumped from oil rigs. the hydrocarbons in petrol are alot lower than diesel making it more flamable than diesel. diesel has higher coefficient than petrol thus is why it is used in more heavyer vehicals for transportation.

a fuel shut off solenoid runs off electrical current.the fuel pumps through it at its average speed. the solenoid is desinged to pick up anything weird in the flow such as heat, if a thing like heat is picked up in the solenoid it is sent an eltrical current wich shuts the valve stopping fuel from going anyfurther into the engin.  A device like this is a must as it can prevent any further fuel being added to a fire or broken part on the boat if it is carshed or involved in a accident.

a four stroke sytem is  described in a 4 step plan, intake compression power and exhaust. the intake involves the mixture of air and fuel weather that be carb or injection, the inlet valve opens and lets in the mixture of air and fuel into the boar.  the compression part is when the piston pumps up compressing the mixture. power is when the spark plug ignites  the compressed mixture and forces the piston on its down stroke, exhaust is when the out let valve opens and the piston pumps up forcing the burnt mixture in to the exhaust pipe and out into the atmospher.

more to come.....