Snowmobile Arctic Cat (2002 year). Instruction - part 62

 

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Snowmobile Arctic Cat (2002 year). Instruction - part 62

 

 

4-41

4

AE114

AE141

Arctic Cat Batteryless 

EFI System

The Arctic Cat Batteryless EFI System operates off a

series of coils located on the stator.

The batteryless EFI system is made up of the follow-

ing components.

1. Charge coils (1 and 2) which are located on the

stator provide AC voltage to operate the CDI unit.

The CDI unit is located within the ECU. The AC

voltage is converted to DC voltage within the

ECU.

2. A fuel pump coil located on the stator operates the

low voltage, high output fuel pump. At cranking

speed, the high output fuel pump provides enough

fuel to charge the fuel rail.

3. An injector coil located on the stator provides the

injectors with DC voltage for operation through

the ECU.

4. A lighting coil located on the stator plate provides

output to operate accessories and the lighting

system.

5. An electrical control unit (ECU) calculates input

from five sensors (intake air temperature sensor,

water temperature sensor, throttle position sensor,

ignition timing sensor, barometric pressure sensor)

to provide the engine with the correct fuel mixture

and timing for optimum operation.

EFI FEATURES

1. Automatic compensation for temperature.

2. Automatic compensation for altitude.

3. Optimum throttle response through high pressure

injection.

4. Quick starting in every condition.

5. Improved fuel efficiency with maximum mileage

in every condition.

6. Engine RPM more stable in every condition.

PRECAUTIONS

0729-325

! WARNING

Whenever working on the fuel system if a fuel hose
is removed from any component, slowly bleed the
pressure from the hose into an absorbent towel
before removing the hose from the component.

! WARNING

 Always tighten fuel hose clamps securely.

! CAUTION

Always use resistor-type spark plugs and spark
plug caps. Non-resistor components will cause
the ECU to malfunction.

4-42

STARTING

1. To start an engine for the first time or after

performing service work on the fuel system, place

the emergency stop switch and the ignition switch

in the ON position. Disconnect the yellow water

temperature sensor lead wire at the ECU. Crank

the engine over 6-8 times with the recoil starter.

With the water temperature sensor lead

disconnected, the fuel system will call for

maximum mixture and the system will charge

faster. After 6-8 brisk pulls on the recoil starter

rope, reconnect the yellow sensor lead. The engine

should start in 2-3 additional pulls. After charging

the fuel system, the engine should start in 3-4 pulls

when cold.

2. Start the engine without compressing the throttle.

When the engine starts for the first time, do not

touch the throttle. It will idle slowly and may stop.

Repeat this procedure until the engine starts and

builds RPM on its own. This may require 3-4

restarts. Once the engine has been started and run,

the next cold start should occur in 2-3 pulls of the

recoil starter rope.

FLOODED ENGINE

If the engine should become flooded, set the brake

lever lock, compress the throttle lever to the full-open

position, and crank the engine over until it starts and

clears itself. Release the brake lever lock.

FUEL SYSTEM

The EFI fuel system consists of the following compo-

nents.

1. Gas tank

2. Electric high output fuel pump

3. Two pick-up valves with micron screens

4. High-pressure fuel hose

5. Fuel rail

6. Fuel pressure regulator *

7. Throttle body assembly

8. Injectors

9. Fuel return hose (600 cc)

10. ECU

* On the 800 cc, the regulator is in the fuel pump.

These above components are grouped into the fuel

handling system. They work together along with five

electrical sensors (listed below) and the ECU to pro-

vide the engine with a precise fuel mixture for com-

bustion. The five sensors are the following.

1. Ignition Timing Sensor

2. Intake Air Temperature Sensor

3. Water Temperature Sensor

4. Throttle Position Sensor

5. Barometric Pressure Sensor

The fuel is first drawn into the electric fuel pump

through two pick-up valves and hoses. The fuel is then

routed through a high-pressure fuel hose to the fuel

rail.

The fuel pressure is maintained at 37.9 ± 2.2 psi (600

cc) and 48 ± 2.2 psi (800 cc) in the fuel rail by the fuel

regulator. If pressure exceeds this amount, the regula-

tor opens and returns excess fuel to the gas tank

through the fuel return hose (600 cc).

With the fuel pressure maintained at a constant psi, the

ECU evaluates the information it receives from the

five electrical sensors and opens the injectors for pre-

cise periods of time (pulse widths) to meet engine

demands.

„

NOTE: The entire EFI system depends on all

coils functioning properly on the stator.

Individual EFI 

Components

ECU

The ECU is the brain of the EFI system. It uses five

sensor inputs to determine the correct fuel/air ratio for

the engine given the existing conditions of altitude and

temperature.

AO152D

If any of the sensors should fail while the engine is

running, the ECU will sense a problem and go into a

“limp home” mode. This is an over-rich condition and

will greatly reduce performance. However, the engine

will be protected from a possible lean condition and

engine damage.

4-43

4

The ECU is equipped with a light emitting diode

(LED), which will flash a series of pulses when a prob-

lem exists with any of the sensors. By observing the

code, the technician can determine the problem sensor

by comparing the code flashed with the trouble code

chart (see Trouble Codes in this sub-section).

AO153D

„

NOTE: There are no repairs that can be made to

the ECU.

If the ECU is not receiving current from one of the

output coils on the stator, that circuit will not operate.

Coils on the stator are the capacitor charge coil which

operates the CDI within the ECU, the injector coil

which operate the injectors, the fuel pump coil which

operate the fuel pump, and the lighting coil which

operates all accessories and the lighting system. Refer

to the wiring diagram in this sub-section.

AO132D

INTAKE AIR TEMPERATURE SENSOR

AO135D

The intake air temperature sensor is mounted on the

front of the air-intake silencer. Its purpose is to sense

air temperature entering the air-intake silencer and

engine. The ECU sends current to this sensor, and

(depending on the temperature) the sensor will pass a

certain amount of current through the sensor to

ground. The ECU measures how much current passes

through the sensor to ground. From this measurement,

the ECU determines the air temperature and calculates

the fuel/air mixture ratio. This sensor is very sensitive

to temperature change. Resistance will drop as the

temperature rises.

WATER TEMPERATURE SENSOR

AO069

The water temperature sensor is located on the bottom

of the thermostat manifold. This sensor is very sensi-

tive to temperature change. The ECU measures the

current flow through the sensor to ground. From this

measurement, the ECU can determine the engine cool-

ant temperature and calculate the correct fuel/air mix-

ture ratio.

„

NOTE: If the coolant temperature rises above

80° C (176° F), the temperature sensor starts to
close which also will start to richen the fuel mix-
ture. Once the engine coolant temperature reaches
93° C (200° F), the temperature sensor is fully
closed which will signal the ECU to go into the rich
mode to protect the engine from overheating. At
this time, the overheat light will be illuminated. The
overheat sensor, which illuminates the overheat
light, closes at 93° C (200 ° F) ± 6° F.

THROTTLE POSITION SENSOR

AO136D

4-44

The throttle position sensor, located at the end of the

throttle shaft, is a potentiometer (a potentiometer is,

essentially, a voltage divider). This sensor transforms

the throttle-valve position into output voltage to the

ECU. In addition, the sensor detects the opening or

closing speed of the throttle valve and feeds that rate

of voltage change to the ECU.

„

NOTE: The input from the throttle position sen-

sor is one of the main inputs for the ECU calcula-
tion of fuel/air mixture ratio.

IGNITION TIMING SENSOR

0729-627

This sensor is located on the top of the magneto case

near the cylinder on some models. On other models the

sensor is located inside the magneto case next to the

flywheel, and on these models, the recoil starter and

the flywheel must be removed to access the sensor.

This sensor is triggered by a small metal disc precisely

mounted to the flywheel flange. Each time the metal

disc rotates past the sensor, a signal is sent to the ECU.

From this signal, the ECU determines ignition and

injection timing and RPM.

BAROMETRIC PRESSURE SENSOR

AO155D

This sensor is located inside the ECU and is part of the

ECU unit. Its purpose is to sense atmospheric pressure.

From this information, the ECU determines the correct

fuel/air mixture ratio.

„

NOTE: This sensor is not replaceable. If it should

fail, the ECU must be replaced.

FUEL INJECTORS

AO139D

The fuel injectors are positioned in the top of each

throttle body. O-rings seal the top and bottom of each

injector, and they are held in position by a locking

plate secured to the fuel rail.

AO140D

The fuel injector is an electromagnetic injection valve

controlled by a signal from the ECU. The coil used in

the injector is a high-pressure resistance type. The

ECU determines the optimum fuel injection time and

duration based on signals from the five sensors.

When voltage is sent to the fuel injector, it energizes

the coil and opens the needle valve, thereby injecting

fuel. Because the fuel pressure (pressure differential

between fuel line and manifold) is kept constant, the

amount of fuel injected is determined by the duration

of time the valve is open.

The injectors are coded with symbols (

Q

-

O

-

V

). When

replacement of a fuel injector is necessary, the injector

must be replaced with an injector of the same code

symbol.

 

 

 

 

 

 

 

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