Snowmobile Arctic Cat (2002 year). Manual - part 61

4-37

MAJOR TUNING COMPONENTS

To assist you in selecting four major tuning components of the VM-style and TM-style carburetors, listed
below are the jet needles, needle jets, pilot jets, and piston/throttle valves (slides) on charts according to
their size.

TUNING1

NOTE: The above needle jets may come in differ-

ent types; for example, (159) - (166) - (480) - (224).
When selecting a new needle jet, use the correct
series or type.

JET

NOTE: The above chart shows the average per-

formance of a given needle between 1/4 and 3/4
throttle. Needles are constructed in such a way
that at any given point, the needle could be richer
or leaner than the rating it has.

PILOT

PISTON

4-38

Troubleshooting

Fuel System

(Carbureted)

Problem: Carburetor Too Rich (0-1/4 Opening)

Condition

Remedy

1. Choke plunger will not seat

2. Pilot air screw (VM-style) too far in

3. Fuel mixture screw (TM-style) too far out

4. Pilot air passage obstructed — damaged

5. Float/inlet needle obstructed — damaged —

adjusted incorrectly

6. Pilot jet loose

1. Adjust — service — replace choke cable —

plunger assembly

2. Adjust pilot air screw

3. Adjust fuel mixture screw

4. Remove obstruction — replace pilot air screw

— carburetor

5. Remove obstruction — replace inlet needle

— float — adjust float tab

6. Tighten pilot jet

Problem: Carburetor Too Rich (1/4-3/4 Opening)

Condition

Remedy

1. Pilot air screw (VM-style) too far in

2. Fuel mixture screw (TM-style) too far out

3. Needle jet — jet needle worn — adjusted

incorrectly — incorrect

4. Pilot air passage obstructed — damaged

5. Pilot jet loose

6. Float/inlet needle obstructed — damaged —

adjusted incorrectly

7. Main jet loose — too large

8. Primary air passage obstructed

1. Adjust pilot air screw

2. Adjust fuel mixture screw

3. Replace needle jet — replace — adjust jet

needle E-clip

4. Remove obstruction — replace pilot air screw

— carburetor

5. Tighten pilot jet

6. Remove obstruction — replace inlet needle —

float — adjust float tab

7. Tighten — replace main jet

8. Remove obstruction

Problem: Carburetor Too Rich (3/4-WOT Opening)

Condition

Remedy

1. Main jet loose — too large

2. Float/inlet needle obstructed — damaged —

adjusted incorrectly

3. Needle jet — jet needle worn — adjusted

incorrectly — incorrect

1. Tighten — replace with smaller main jet

2. Remove obstruction — replace inlet needle —

float — adjust float tab

3. Replace needle jet — replace — adjust jet

needle E-clip

4-39

Problem: Carburetor Too Lean (0-1/4 Opening)

Condition

Remedy

1. Choke plunger remains seated

2. Pilot air screw (VM-style) too far out —

damaged

3. Fuel mixture screw (TM-style) too far in —

damaged

4. Throttle valve sticks open — damaged — worn

5. Pilot jet — outlet obstructed

6. Float/inlet needle obstructed — damaged —

adjusted incorrectly

7. Float bowl vent hose (TM-style) obstructed —

kinked — damaged

1. Adjust — service choke cable — plunger

assembly

2. Adjust — replace pilot air screw

3. Adjust — replace fuel mixture screw

4. Service — replace throttle valve — throttle

cable — spring

5. Remove obstruction

6. Remove obstruction — replace inlet needle —

float — adjust float tab

7. Service — replace float bowl vent hose

Problem: Carburetor Too Lean (1/4-3/4 Opening)

Condition

Remedy

1. Pilot air screw (VM-style) too far out —

damaged

2. Fuel mixture screw (TM-style) too far in —

damaged

3. Needle jet obstructed

4. Pilot jet — outlet — main jet obstructed

5. Float/inlet needle obstructed — damaged —

adjusted incorrectly

6. Jet needle E-clip position incorrect

7. Float bowl vent hose (TM-style) obstructed —

kinked — damaged

1. Adjust — replace pilot air screw

2. Adjust — replace fuel mixture screw

3. Remove obstruction

4. Remove obstruction

5. Remove obstruction — replace inlet needle —

float — adjust float tab

6. Adjust E-clip

7. Service — replace float bowl vent hose

Problem: Carburetor Too Lean (3/4-WOT Opening)

Condition

Remedy

1. Main jet obstructed — too small

2. Float/inlet needle obstructed — damaged —

adjusted incorrectly

3. Needle jet — jet needle obstructed

4. Float chamber vent hose (TM-style)

obstructed — kinked — damaged

1. Remove obstruction — replace with larger main

jet

2. Remove obstruction — replace inlet needle —

float — adjust float tab

3. Remove obstruction

4. Service — replace float chamber vent hose

Problem: General Fuel System (Engine Cuts Out at High RPM)

Condition

Remedy

1. Fuel delivery inadequate

2. In-line fuel filter obstructed — damaged

3. Gasoline contaminated

4. Gas-tank vent — hose obstructed

1. Repair — replace fuel pump — impulse hose

2. Remove obstruction — replace in-line fuel filter

3. Replace gasoline — de-ice — clean carburetors

4. Remove obstruction — replace vent — hose

Problem: General Fuel System (One Cylinder Runs Lean)

Condition

Remedy

1. Carburetor-to-cylinder air leak

2. Carburetors (VM-style) not aligned vertically

3. Primary compression (crankcase) low

4. Carburetors not synchronized

1. Repair — replace gaskets — flanges — service

intake ports — tighten clamps

2. Align carburetors vertically

3. Troubleshoot engine

4. Synchronize carburetors

4-40

Fuel System

(Batteryless EFI)

This sub-section has been organized for servicing EFI

fuel systems; however, some components may vary

from model to model. The technician should use dis-

cretion and sound judgment when removing/ disas-

sembling and assembling/installing components.

All 2002 EFI models are equipped with the batteryless

EFI system.

NOTE: Some illustrations and photographs used

in this section are used for clarity purposes only
and are not designed to depict actual conditions.

Fuel System

(Batteryless EFI)

Table of Contents

(Kokusan Mode)................................................. 4-53

Testing Individual EFI Components....................... 4-54
Peak Voltage Tests and Specifications

(2002 Models) .................................................... 4-56

Throttle Position Sensor ........................................ 4-57
Throttle Body Flange............................................. 4-57
Throttle Body Assembly ........................................ 4-58
Throttle Cable........................................................ 4-59
Basic EFI System Information............................... 4-60
EFI Component Voltage/Resistance Chart -

Air Temperature ................................................. 4-61

EFI Component Voltage/Resistance Chart -

Water Temperature ............................................ 4-62

EFI EPROM Chip Usage Chart (1991-1998) ........ 4-63
EFI EPROM Chip Usage Chart (1999-2001) ........ 4-64
Troubleshooting Fuel System (EFI)....................... 4-64
EFI Wiring Diagrams ............................................. 4-65

Introduction

The batteryless EFI system is lightweight in design

and is made up of a number of components which are

explained in this sub-section. The batteryless EFI sys-

tem eliminates the worry of battery maintenance or

changing main jets to compensate for altitude or tem-

perature. This EFI system will provide quick and easy

starting under all conditions.

The electrical control unit (ECU) has a self-diagnostic

mode built in. It is a very valuable factor in trouble-

shooting. Once the problem area has been determined

from the trouble code flashed by the LED (light emit-

ting diode) located under the left end of the ECU, fol-

low the troubleshooting procedure in this sub-section.

When troubleshooting the batteryless EFI system, spe-

cial tools are required. These special tools are the fol-

lowing.

A. EFI Analyzer (p/n 0644-212)

B. Fuel Pressure Tester (p/n 0644-203)

C. Fluke Model 73 Multimeter (p/n 0644-191)

D. Peak Voltmeter (p/n 0644-300)

If the EFI analyzer at your dealership was purchased

before February 1, 1998, it must be updated with an

Update Kit (p/n 0644-256) before it can be used to

troubleshoot any of the 1997-2002 batteryless EFI

models (without the Arctic Power Valve System). The

update kit consists of a wiring harness and a new

EPROM chip. The update kit can be ordered from your

distributor or the Arctic Cat Parts Department.

NOTE: Troubleshooting EFI engines with the

APV system should be done with the Arctic Cat
EFI Analyzer (p/n 0644-342). To update your exist-
ing EFI Analyzer, order Kit (p/n 0644-341).

AE131

AE124

Content .. 59 60 61 62 ..