Snowmobile Arctic Cat 2-Stroke (2007 year). Manual - part 62

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SNO-142

0644-493

AE114

0744-048

Arctic Cat EFI System

The Arctic Cat EFI System operates off a series of

coils located on the stator.

The EFI system is made up of the following compo-

nents.

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

stator provide AC voltage to the ECU/CCU where

AC voltage is converted to DC voltage.

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 the CCU to operate accessories and the

lighting system.

5. An electrical control unit (ECU) calculates input

from sensors (intake air temperature sensor, cool-

ant temperature sensor, throttle position sensor,

ignition timing sensor, barometric pressure sensor,

and on the 800 cc, a knock 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.

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PRECAUTIONS

0729-325

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 located in the fuel pump

7. Throttle body assembly

8. Injectors

9. ECU

These components are grouped into the fuel handling

system. They work together along with electrical sen-

sors (following list) and the ECU to provide the engine

with a precise fuel mixture for combustion. The sen-

sors are the following.

1. Ignition Timing Sensor

2. Intake Air Temperature Sensor

3. Coolant Temperature Sensor

4. Throttle Position Sensor

5. Barometric Pressure Sensor

6. Knock Sensor (800 cc)

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 specified psi in the

fuel rail by the fuel regulator.

With the fuel pressure maintained at a constant psi, the

ECU evaluates the information it receives from the

electrical sensors and opens the injectors for precise

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 sensor

inputs to determine the correct fuel/air ratio for the

engine given the existing conditions of altitude and

temperature.

MS396

! 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.

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If any of the sensors should fail while the engine is

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

“fail safe” 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.

The ECU is equipped with a check engine light in the

speedometer/tachometer which will flash a series of

pulses when a problem 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 appropriate Diagnostic

Codes in Section 1).

„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 charge coils which operate

the ECU, the injector coil which operates the injectors,

the fuel pump coil which operates the fuel pump, and

the lighting coil/chassis control unit which operates all

accessories and the lighting system. Refer to the wir-

ing diagram.

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.

COOLANT TEMPERATURE SENSOR

AO069

The coolant temperature sensor is located on the lower

crankcase. This sensor is very sensitive to temperature

change. The ECU measures the current flow through

the sensor to ground. From this measurement, the ECU

can determine the engine coolant temperature and cal-

culate the correct fuel/air mixture ratio.

„NOTE: If the coolant temperature rises above
80° C (176° F), the temperature sensor starts to
richen the fuel mixture. At this time, the check
engine light will flash constantly. Once the engine
coolant temperature reaches the specified temper-
ature 93° C (200° F), the temperature sensor will
signal the ECU to go into the rich mode to protect
the engine from overheating. At this time, the
check engine light will be constantly on.

THROTTLE POSITION SENSOR

CM202A

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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 inside the magneto case next to

the flywheel, and 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

FS020A

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

FS021

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.

FS022A

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

) and are

color-coded yellow and green. When replacement of a

fuel injector is necessary, the injector must be replaced

with an injector of the same code symbol and color.

! CAUTION

Do not replace an injector with one of a different
code symbol or color. Severe engine damage may
occur.