Throttle Body Assembly; Fuel Pressure Regulator - Arctic Cat Sno Pro 120 Service Manual

The fuel system and the ignition system remain two sepa-
rate systems. In a no-start situation, first determine if the
problem is caused by lack of spark or by a fuel delivery
problem or by an internal engine condition (low cylinder
compression for example).
Once the problem area has been determined, check the
components involved using the Fluke Model 77 Multime-
ter or the EFI Analyzer depending on the test being made.

Fuel Pressure Regulator

1. Using the Fuel Pressure Test Kit, connect the tester
to the regulator fuel inlet.
 NOTE: A short piece of 3/8 in. I.D. hose will be
needed to make the above connections.
2. Pressurize the regulator to 28-31.3 psi. Turn the pres-
sure tester shut off valve to the OFF position.
Observe the gauge for several minutes and note any
loss of pressure. If pressure begins to drop, the cause
may be a ruptured diaphragm, worn spring, or leak-
ing valve. If the regulator fails to build or maintain
pressure, replace the regulator.
 NOTE: If the pressure drops, check the hose con-
nections to ensure no leaks exist.

Throttle Body Assembly

REMOVING (500/800 cc)
 NOTE: The expansion chamber, shock mount
bracket support (800 cc), and air silencer must be
removed for this procedure (see Section 3).
1. Disconnect the wiring harness from each injector and
from the throttle position sensor.
2. Remove the coolant hoses from the throttle body
assembly and plug them to prevent leakage.
3. Remove the fuel supply hose from the fuel rail.
WARNING
Since the fuel supply hose may be under pressure, remove
it slowly to release the pressure. Place an absorbent
towel around the connection to absorb gasoline; then
remove the hose slowly to release the pressure. Always
wear safety glasses when removing the fuel hoses.
4. Loosen the flange clamps.
5. Remove the oil pump control rod (800 cc).
6. Slide the throttle body assembly out of the flanges;
then loosen the jam nut securing the throttle cable
and remove.
7. Remove the throttle body assembly.
INSTALLING (500/800 cc)
1. Attach the throttle cable to the throttle body; then
secure with jam nut. Secure the coolant hoses to
throttle body assembly.
2. Place the throttle body assembly into position. Make
sure the flanges and boots are positioned properly.
Secure with flange clamps.
3. Where applicable, connect the oil pump control rod.
4. Connect the fuel supply hose to the fuel rail.
5. Connect the wiring harness to each injector and
throttle position sensor.
CAUTION
Verify the oil pump rod linkage is properly installed or
damage to the engine will occur.
 NOTE: Install the air silencer, shock mount bracket
support (800 cc), and the expansion chamber (see
Section 3).
6. Place the rear of the snowmobile on a shielded safety
stand and start the engine without touching the throt-
tle. It may idle slowly and stop. Restart using the
same procedure until the engine starts and builds
RPM on its own.
CAUTION
When installing the throttle bodies, make sure the
gasline hose is properly routed to avoid premature
wear and/or contact with exhaust components.
7. Check the cooling system and adjust the throttle
cable as necessary.
REMOVING/DISASSEMBLING
(1100 cc Non-Turbo)
 NOTE: To remove the throttle body assembly, it is
necessary to remove the air silencer (see Section 3).
On the F/M/XF, the seat and gas tank must also be
removed.
1. Remove the coolant hoses and MAP sensor hoses
from the throttle body.
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