Cub Cadet RZT 50 Operator's Manual page 42

Carburetor Troubleshooting and
Adjustments
In compliance with government emission standards,
the carburetor is calibrated to deliver the correct fuel-
to-air mixture to the engine under all operating
conditions. The high speed mixture is set at the
factory and cannot be adjusted. The low idle fuel
adjustment screw (if equipped) is also set at the
factory and normally does not require adjustment. See
Figure 15.
Low Idle
Mixture Screw
Figure 15. Carburetor.
Low Idle Mixture Screw
Idle Speed (RPM)
Adjustment Screw
Element
Figure 16. Carburetor Adjustment Access Locations
(Latch Removed For Clarity).
Troubleshooting
If engine troubles are experienced that appear to be
fuel system related, check the following areas before
adjusting the carburetor.
• Make sure the fuel tank is filled with clean, fresh
gasoline.
• Make sure the fuel tank cap vent is not blocked
and that it is operating properly.
• If the fuel tank is equipped with a shut-off valve,
make sure it is open.
• If the engine is equipped with an in-line fuel filter,
make sure it is clean and unobstructed. Replace
the filter if necessary.
12
• Make sure fuel is reaching the carburetor. This
• Make sure the air cleaner element is clean and all
If, after checking the items listed above, the engine is
hard to start, runs roughly, or stalls at low idle speed,
it may be necessary to adjust or service the
carburetor.
Adjust Carburetor
Idle Speed
NOTE: Some engines may have a fixed (capped) idle
(RPM)
Adjustment
Screw
Fuel Solenoid
1. Idle Fuel Adjustment: with the engine stopped,
NOTE: The tip of the low idle fuel adjusting screw is
2. Preliminary Settings: Turn the adjusting screw
3. Start the engine and run at half throttle for 5 to 10
4. Low Idle Speed (RPM) Setting: Place the throttle
*NOTE: The actual low idle speed depends on the
5. If proper operation is not restored after adjusting,
includes checking the fuel lines and fuel pump for
restrictions or faulty components, replace as
necessary.
air cleaner element components are fastened
securely.
fuel adjusting screw or limiter cap. On these
engines, do not attempt steps 1 and 2 below.
Proceed directly to Step 3. On limiter
equipped models, adjustment can only be
performed within the limits allowed by the
cap.
turn the low idle fuel adjusting screw in
(clockwise) until it bottoms lightly. See Figures 15
and 16.
tapered to critical dimensions. Damage to the
needle tip and the seat in carburetor body
will result if the needle is forced.
out (counterclockwise) from lightly bottomed
2-1/4 turns.
minutes to warm up. The engine must be warm
before making final settings (steps 4, 5, and 6).
control into the "idle" or "slow" position. Set the
low idle speed to 1200 RPM* (± 75 RPM) by
turning the low idle speed adjusting screw in or
out. Check the speed using a tachometer.
application – refer to equipment
manufacturer's recommendations. The
recommended low idle speed for basic
engines is 1200 RPM. To ensure best results
when setting the low idle fuel needle, the low
idle speed must not exceed 1200 RPM
(± 75 RPM).
carburetor servicing by an authorized Kohler
Engine Service Dealer may be required.