Snowmobile Polaris IQ (2007-2008 year). Manual - part 23

4.10

Fuel Systems

FUEL PUMP

Fuel Pump Overview

The impulse-powered fuel pump on carbureted engines works
by using the positive and negative pressure pulses generated by
the movement of the pistons inside the engine crankcase.

When the MAG piston is on the upward stroke, negative
(vacuum) pressure pulse is applied to the fuel pump. This action
draws fuel into the pump from the fuel tank.

When the MAG piston is on the downward stroke, a positive
pressure pulse is applied to the fuel pump. This action forces
fuel from the intake-side of the pump to the supply-side, then to
the carburetors.

A series of check valves prevents fuel from being drawn out of
the carburetors on the vacuum stroke or forced back into the fuel
tank during the pressure stroke.

Maintenance

The impulse operated-powered fuel pump does not require any
specific scheduled maintenance. However, the following
procedures should be observed:

• Operation

The pump may be checked for operation by removing the fuel
supply line from the carburetor and placing it into a container.
With the engine idling at approximately 2000 RPM, a steady
flow of fuel should be visible.

• Cleaning

The impulse line must be disassembled and cleaned of foreign
material in the event of piston or other internal engine part
failures which produce fragments.

• Inspection

Disconnect impulse line from pump. Connect a Mity Vac to
impulse fitting (or line) and apply 4-6 PSI pressure. Diaphragm
should hold pressure indefinitely.

FUEL IN (FROM TANK)

IMPULSE HOSE FITTING

(ALWAYS ON BACK OF PUMP)

FUEL OUT

4.11

Fuel Systems

4

CARBURETOR SERVICE

Disassembly

1.

Remove the carburetor from the engine before
disassembling. Clean the outside of the carburetor
thoroughly with solvent. Do not use compressed air to dry
at this time.

2.

Remove all top cap screws (1), top cap (2) and gasket (3).

3.

Locate the arm screw (4) and loosen it just enough to move
the arm (5) out of the way so that you can remove the needle
(6) e-clip and the plastic washer from the throttle slide.

NOTE: Keep track of the plastic washer (9), and
place it so it is on the top of the throttle valve when
installing the needle and e-ring back into the
carburetor.

4.

Inspect the needle (7), e-clip (8), and plastic washer (9) for
wear.

5.

Remove the four screws (10) on the funnel face.

6.

Turn throttle shaft so the throttle slide (11) slides open all
the way. 

7.

With slide fully open, pull funnel (12) out from the bottom
first. Inspect the gasket (13).

8.

Check for wear on the faces of the slides.

CAUTION

W

EAR

 

EYE

 

PROTECTION

 

WHEN

 

USING

 

COMPRESSED

 

AIR

 

OR

 

WHEN

 

USING

 

CLEANING

 

SOLVENTS

. R

EVIEW

 

ALL

 

FUEL

 

SYSTEM

 

WARNINGS

 

LOCATED

 

AT

 

THE

 

BEGINNING

 

OF

 

THIS

 

CHAPTER

 

BEFORE

 

PROCEEDING

.

1

2

3

4

5

6

7

8

9

10

11

12

13

4.12

Fuel Systems

9.

Inspect e-rings, plate, spring, and rings (14) connecting the
slide to the lever if needed.

10. Remove water trap/drain plug (15) and single screw (16)

on the bottom of the carburetor.

11. Remove and drain the float bowl (17).

NOTE:  Float bowl will not come off unless the water
trap/drain plug and screw are removed.

12. Remove the two screws (18) holding the float/needle and

seat assembly (19) in position and remove this assembly.

13. Inspect the contents for wear and debris.

14. Remove and inspect the main jet (20), pilot jet (21), and

starter jet (22). Clean them out.

15. Remove the air jet screw if so equipped.

16. Clean out all passages in carburetor body with carburetor

cleaner. Dry all passages and jets with compressed air.

17. Replace gaskets and any parts that show wear or damage.

18. Repeat steps 1-18 for disassembly for the other carburetor

if needed.

14

15

16

17

18

19

20

22

21

4.13

Fuel Systems

4

Assembly

1.

Install the main jet (20), pilot jet (21), and starter jet (22).

2.

Install float/needle & seat assembly (19).

3.

Place carburetor in an inverted position.

4.

Connect a pressure tester (PN 2870975) to fuel inlet fitting.
Apply 5 psi pressure and observe for one minute. The
needle and seat should hold pressure indefinitely. If the
pressure drops, carefully inspect the needle and the needle
seat. The needle can be replaced (needle supplied with float
and seat).

5.

Carefully inspect float bowl gasket and replace if
necessary.

6.

Install float bowl (16) on carburetor with water trap/drain
plug (15) and single screw (16) on the bottom of the
carburetor.

7.

If throttle slide was removed, install throttle slide (11) so
that the wider face is facing the engine side of the
carburetor.

8.

Install the funnel gasket (13) and funnel (12) onto the
carburetor. You will have to lift the throttle slide up and
place the smaller face into the funnel area.

9.

Install funnel screws (10).

10. Install the e-clip (8) in the desired position on the jet needle

(7).

11. Slide the plastic washer (9) on the jet needle so that it is

positioned to rest on top of the throttle valve when
assembled.

12. Install carburetors on engine.

13. Replace top cap gaskets (3), cover (2) and screws (1).

14. Check throttle lever free play.