Single point fuel injection uses a single injector or cluster of injectors located on the intake manifold to directly spray fuel into the throttle bores. It has advantages like precise fuel control for engine conditions and reduced fuel consumption. However, there can be a time lag for driver input and uneven fuel delivery between cylinders. The system operates with a single electromagnetic injector intermittently injecting fuel above the throttle valve, controlled by opening and closing. Engine sensors track speed, load, temperature and throttle position to regulate the fuel injection amount from a simple turbine pump.

1. Single point injection system
 This is a systemwhere a single injector or a group of injectors clustered together in one
centralized spot on the intake manifold.
 The throttle unit resembles a carburetor except that there is no fuel bowl float or
metering Jets.
 Fuel is sprayed directly into the throttle bores by the injectors.
Advantages of single point fuel injection
1. Only one fuel injector.
2. The systempressure is not dependant on the intake air pressure.
3. Reduced fuel consumption-there is precise adaptation of engine conditions.
4. Improved performance through greater latitude if the intake tracts.
5. Large distance of heat stressed parts which leads to fewer steam bubbles and a cheaper
delivery pump.
Disadvantage or challenges of single point fuel injection
1. There is time lag since the timing is done by the camshaft when a driver makes sudden
changes.
2. The amount of fuel delivered to the cylinder is not the same for all of them, one cylinder
side receives more fuel than the other due to the engine shape.
Operation
 There is only one electromagnetic fuel injector for all four cylinders
injecting fuel intermittently abovethe throttle valve.
 The injection amountis controlled by opening or closing of fuel injector.
 Since the supply pressureis low, a simple turbine pump is used which is
more efficient than a roller vanepump.
 The systempressuredoes not have to be regulated.
 The control unit keeps track of all essential data, speed, load, temperature
of the engine and also the throttle valveangle and position.
Construction
The single point fuel injectionis made up of following parts.
 Fuel entrance

2.  Air intake
 NThrottle plate
 Admission
 Injector
 Engine
Some of the sensors used
 Inductive pick up- which determines the position
of the crankshaft and speed of the engine to
calculate injection time.
 Lambda probe-or Oxygen sensor help to
determine if the air fuel ratio of a combustion
engine is richer or lean by measuring oxygen
proportion.
 Temperature sensors
 Throttle potentiometer.