Carburetor; Carburetor Adjustments; Service And Adjustments - Craftsman WEEDWACKER 358.798430 Operator's Manual

SERVICE AND ADJUSTMENTS
Carburetor adjustment is critical and if done improper-
ly can permanently damage the engine as well as the
carburetor. Please read all/nstructions and consult the
Troubleshooting section of this manual before begin-
ning this process. If the engine does not operate
according to these instructions after repeating the
adjusting steps, do not use the unit. For further assis-
tance, please call our customer assistance hoUine at
1-800-235-5878.
WARNING:
MAKE CARBURETOR ADJUSTMENTS WITH
THE LOWER END SUPPOR_D TO PREVENT
SEMI-AUTOMATIC HEAD FROM CONTACTING
ANY OBJECT. HOLD UNIT WITH YOUR HAND.
THE SEMI-AUTOMATIC HEAD WILL BE SPIN-
NING DURING MOST OF THIS PROCEDURE.
WEAR YOUR PROTECTIVE EQUIPMENT AND
OBSERVE ALL SAFETY PRECAUTIONS.
IN MIXTURE ADJUSTMENT, RECHECK IDLE
SPEED AFTER EACH ADJUSTMENT. THE
SEMI-AUTOMATIC HF-_D MUST NOT MOVE AT
IDLE SPEED,
If engine does not start, it may be flooded. If in doubt read
.the section on flooded engine in (he starting section of this
manual prior to beginning any adjustments,
The carl_Jretor has been adjusted at the factory for sea
level conditions. Adjustments may become necessary ifthe
unit is used at significantly higher altitudes or if you notice
any of the following conditions:
• Engine will not idle. See "Idle Speed Adjustment" and
"Mixture Speed Adiustment'.
• Engine dies or hesitates when it should accelerate. See
"Acceleration Check".
• Loss of cutting power which is not corrected by air filter
cleaning. See "Mixture Speed Adjustment".
NOTE: There are two adjustments on the carburetor.
* The Idle Speed Adjustment.
The Mixture Adjustment.
CARBURETOR PRESETS (FIG. 30)
!f your engine will not start due to suspected improper car-
buretor adjustment, the following presets may be required.
- If used, it is;recommended that al| steps withing the adjust-
ment procedure be completed in order to assure a proper-
ty set carburetor. If presets are not needed, proceed to sec-
tion "Idle Speed Adjustment".
When making adjustments, be careful not to force the plas-
tic limiter caps beyond the stops or damage will occur.
Very small adjustments can affect engine performance, it is
important to make slight adjustments and test performance
before proceeding. Each adjustment should be no more
than 1t16th of a turn.
• Turn the mixture adjustment fully counterclockwise to the
limiter cap stops+
; Turn idle speed adjustment clockwise one full turn.
If engine fails to start after performing carburetor presets,
the unit may be flooded. Review the "Difficult Starting"
section of the manua!+ If problems continue, call the 1-
800 number listed on the front cover of this manual for
further assistance.
• Start the engine and operate for three (3) minutes to
warm up. Go to "Adjusting Procedure".
- 20 -
MIXTURE SCREW
SCREW COVER
Figure 30
ADJUSTING PROCEDURE
iDLE SPEED ADJUSTMENT
• Allow the warm engine to idle.
• Adjust the idle Speed until the engine continues to run
without stalling and without the semi-automatic head
turning.
- Turn screw clockwise to increase engine speed ff
engine stalls or dies.
- 7[lrn screw counte_l_=_'se to slow engine down.
• Follow instructionsin _cceleration Check".
o No further adjustments are necessary if performance is
satisfactory.
MIXTURE ADJUSTMENT
• Support the lower end so the semi-automatic head is off
the ground and will not make contact with any object. Be
sure the trimmer line is extended to the maximum length
allowed by the line limiter.
• Start the engine. Allow engine to idle, then squeeze
throttle trigger fully.
NOTE: Perform steps below at full throttle,
• Turn mixture screw counterclockwise to the iimiter cap
stop,
• Run engine at full throttle for 30 seconds.
• If engine is running rough, turn mixture screw clockwise
in 1/t6th turn increments until engine just starts to run
smoothly.
• Do not attempt to adjust screw beyond stops as damage
will occur.
After completing adjustments, check for acceleration.
** if the unit accelerates and runs smoothly, no further
adjustments..are=necessary. If r not, proceed to
"Acceleration Check''.
ACCELERATION CHECK
• Allow engine to idle.
• Squeeze trigger fully.
- If performance is satisfactory (engine accelerates
smoothlyl, no further adjustments are necessary.
- If the engine does not accelerate smoothly, turn the
mixture screw counterclockwise a small amount (no"
more than the width of the slot in the adjusting screw).
• Repeat step above until smooth acceleration is obtained.
Do not attempt to adjust the screw beyond the stop as
damage will occur.
NOTE: It may be necessary to repeat "Idle speed
Adjustment' through "Acceleration Check, to obtain correct
adjustments.