Snowmobile Arctic Cat (2004 year). Manual - part 51

4-39

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 (

) 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.

FS025A

NOTE: A green-coded injector is for the 600 cc

EFI STD model; the yellow-coded injector is for all
remaining EFI models.

FUEL PRESSURE REGULATOR

The fuel pressure regulator is attached to the end of the
fuel rail (600 cc STD) and in the fuel pump (600/700
cc “Laydown”/800/900 cc). The fuel pressure regula-
tor maintains the fuel pressure at a constant specified
level.

AO141D

! CAUTION

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

4-40

FS023A

On the 600 cc (STD) when fuel pressure exceeds the
specification, the spring-loaded diaphragm in the regu-
lator opens allowing fuel to flow through the return
hose back to the gas tank.

FUEL PUMP CIRCUIT

The fuel pump and its circuit are provided with current
from the fuel pump coil on the stator.

AO142D

FS024

For this circuit to function correctly, five components
must be in good working order.

Check the following components before considering
the fuel pump assembly to be defective.

A. Fuel pump coil - see coil test procedure.

B. Emergency stop switch and ignition switch

must be ON and in good working order.

C. Fuel pump - see fuel pump test procedure.

D. Wiring harness and connectors - clean the

connectors and test the harness.

E. ECU.

Self-Diagnostic

EFI System

INTRODUCTION

The Electronic Control Unit (ECU) contains a built-in,
self-diagnostic system which detects trouble within the
five-sensor signal network and then flashes a code on
the LED signal light, located under the left end of the
ECU (check engine light in the speedometer/tachome-
ter on “Laydown” engine models).

AO153D

The fuel system and the ignition system remain two
separate systems. In a no-start situation, first deter-
mine if the problem is caused by lack of spark or by a
fuel delivery problem or by an internal engine condi-
tion (low cylinder compression for example).

Using the EFI Ignition Analyzer, equipped with the
update EPROM (chip) and test harness, connect the
test harness to the ECU diagnostic connectors. Con-
nect the test harness red external lead to the positive
terminal of a 12-volt battery and connect the black
external test harness lead to the negative terminal.

If any of the circuits are faulty, a code will now be
flashed by the LED/check engine light.

If no code is flashed, turn on the analyzer. Press the
MENU SELECT buttons until the words KOKUSAN
appear on the display; then press the TEST button. The
analyzer is now programmed for testing the Arctic Cat
Batteryless EFI System.

Using the MENU SELECT buttons, press the button
repeatedly until Memory Problem Diagnosis Test
appears on the display; then press the TEST button. If
any sensors have intermittent problems, they will be
indicated on the display.

Proceed to individual components test procedures cov-
ered throughout this section.

4-41

The code flashed from the LED/check engine light
will first be a number of flashes. Count the number of
flashes and refer to Diagnostic Codes in this sub-sec-
tion. The code repeats itself with approximately a 2-
second delay between each series of flashes.

NOTE: When reading the LED/check engine light

flash sequence, have paper and pencil available to
write down the codes being flashed. More than one
code may be flashed.

Once the problem area has been determined, check the
components involved using the Fluke Model 73 Multi-
meter (p/n 0644-191) or the EFI Analyzer (p/n 0644-
342) depending on which test is being made.

Diagnostic Codes

TROUBLESHOOTING INDIVIDUAL
COMPONENTS

NOTE: With the Arctic Cat Batteryless EFI Sys-

tem, it is ex tre me ly important t hat the ECU
receives the proper current output from four coils
(two charge coils, an injector coil, and a fuel pump
coil) to function as designed. If a problem exists,
these coils should be checked using the following
procedures.

Charge Coil (1)/Charge Coil (2)
Resistance Test

The charge coils power the CDI system and the ECU.
To test these coils, disconnect the 3-wire connector
from the ECU to the stator.

1. Set the meter selector to the OHMS scale and test

between the black/red and green/red wires.

2. The meter must show 17 ohms ± 20%.

3. Test between the green/red and brown/white

wires.

4. The meter must show 17 ohms ± 20%.

NOTE: If either test is not within specifications,

the stator must be replaced. Refer to the wiring
diagram in this sub-section.

Injector Coil Resistance Test

The injector coil located on the stator powers the two
injectors.

1. Disconnect the double-wire plug with two blue/

white leads from the stator to the ECU.

2. Set the meter selector to the OHMS scale.

3. Connect a meter lead to each of the blue/white

leads. The meter must show 19 ohms ± 20%.

NOTE: If reading is not within the specification,

recheck to confirm test results. If still out of toler-
ance, replace the stator.

NOTE: If the resistance test is good, a peak read-

ing voltage test should also be made. Refer to
Peak Voltage Tests and Specifications in this sub-
section.

Fuel Pump Coil Resistance Test

The fuel pump coil powers the fuel pump through the
ECU.

NOTE: With the engine running, there should

12.3-12.9 DC volts supplied to the fuel pump for
operation. To test fuel pump coil resistance, use
the following procedure.

1. Disconnect the double-plug with the two orange

wires from the ECU.

2. Set the meter selector to the OHMS scale. Connect

a meter lead to each of the two orange leads.

3. The meter must show 1.9 ohms ± 20%.

NOTE: If reading is out of tolerance, recheck to

confirm reading. If still out of tolerance, replace
the stator.

NOTE: If the resistance test is good, a peak read-

ing voltage test should also be made. Refer to
Peak Voltage Tests and Specifications in this sub-
section.

Lighting Coil Resistance Test

The lighting coil located on the stator provides AC
power to the lighting system and accessories through a
charging system. To test the lighting coil resistance,
follow this procedure.

1. Disconnect the 3-wire connector at the engine.

2. Set the meter selector to the OHMS scale.

Number of

Flashes

Trouble

Open or short circuit in throttle position

sensor.

Open or short circuit in water

temperature sensor.

Open or short circuit in intake air

temperature sensor.

Open or short circuit in barometric

pressure sensor.

Failure in injector(s).

Failure in servomotor.

Steady

Flash

(600/700 cc)

Coolant Temperature Above 80° C

(176° F).

Constant

(600/700 cc)

Coolant Temperature Above 93° C

(200° F).

4-42

3. Test between the two yellow leads.

4. The meter must show 0.10 ohm ± 20%.

NOTE: If reading is out of tolerance, recheck to

confirm reading. If still out of tolerance, replace
the stator.

ECU

ACTIVATING ECU MEMORY

NOTE: The ECU memory on the 2004 Arctic Cat

Batteryless EFI system (with the APV system) can
be activated only by using the EFI Analyzer (p/n
0644-342) which has had the Update Harness Kit
(p/n 0644-341) installed. For “Laydown” engine
models, use EFI Analyzer Update Kit (p/n 0637-
243).

The ECU has a self-diagnostic mode built into the unit.
It is a very valuable tool in troubleshooting. Once the
problem area code has been flashed by the light emit-
ting diode (LED) located at the end of the ECU (check
engine light in the speedometer/tachometer on “Lay-
down” engine models), follow the troubleshooting
procedure in this sub-section.

The ECU also has a memory mode for determining if
any of the five sensors have intermittently failed. To
activate the memory system, follow these steps.

1. Connect the analyzer test harness to the ECU

diagnostic connector.

2. Connect the analyzer test harness red and black

leads to a 12-volt battery.

3. Turn the analyzer switch ON.

4. Press the analyzer MENU SELECT buttons

repeatedly until KOKUSAN appears on the
display. Once the word KOKUSAN appears on
the display, press the TEST button. The analyzer is
now set up to test the batteryless EFI system.

5. Press the analyzer MENU SELECT buttons

repeatedly until the words Memory Problem
Diagnosis Test appears on the display.

6. Press the analyzer TEST button. If all sensors are

good, SENSORS ALL O.K. will appear on the
display. If any of the sensors have intermittently
failed or are faulty, they will appear on the display.
Proceed then to checking the faulty sensor
individually as covered in this section.

NOTE: Once problem areas have been deter-

mined, always check the component(s) for clean
and tight connections.

7. To erase the memory of the ECU, press the TEST

button once again; then push the MENU SELECT
buttons until Diagnosis Memory Clear appears on
the display. Turn the analyzer OFF and then back
ON again. Reselect KOKUSAN mode; then
proceed to the Memory Problem Diagnosis Test
and push the TEST button. The display should
indicate SENSORS ALL O.K. which indicates the
memory has been cleared.

REMOVING

NOTE: On standard models, there isn’t a test for

the ECU. If a problem is suspected in this unit, try
another ECU. When using another ECU, it must be
a 1997-2003 or 2004 model with a batteryless sys-
tem. The ECU may be sent to the Arctic Cat Ser-
vice Department for testing. Please contact the
Service Department before sending any units.

1. Disconnect the two wiring harness leads (one lead

on “Laydown” engine models) from the front of
the ECU.

2. Remove the four screws securing the ECU to the

air-intake silencer.

3. Remove the ECU.

NOTE: If there are any questions concerning

lead or harness connections, there is an battery-
less EFI system wiring diagram in the back of this
section.

INSTALLING

1. Secure the ECU to the air-intake silencer with the

screws.

NOTE: Make sure the diagnostic connector plug

faces the oil reservoir.

2. Connect the wiring harness to the ECU.

NOTE: Make sure all connectors are clean and

tight. Apply dielectric grease to all connectors.

Testing Individual

Components

NOTE: For individual resistance testing proce-

dures, see Section 5 in this Volume.

NOTE: For the following tests, use the Fluke

Model 73 Multimeter (p/n 0644-191) or a multimeter
of the same quality.

THROTTLE POSITION SENSOR

(All Models)

1. Disconnect the TPS wiring harness connector.

Memory Problem Diagnosis Test

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