MTD 420 - Page 16

SECTION 12" TROUBLE SHOOTING GUIDE
Trouble
Engine fails to
start
Engineruns
erratic
IEngine
overheats
iPossible Cause(s)
Blade controlhandle disengaged.
Spark plugwire disconnected.
Dirty aimleaner.
Primer button not depressed.
Throttlecontrollever not incorrect
starting position(if so equipped).
Fuel tank empty or stale fuel.
Blockedfuel line (it so equipped).
Faulty sparkplug.
Engineflooded.
Unit runningin START position.
Spark plugwire loose.
Blockedfuel line (it so equipped)or
stale fuel.
Vent in gas cap plugged.
Water ordirt infuel system.
Dirty aircleaner•
Carburetorout of adjustment.
Engine oillevel low.
Dirty aimleener:
Air flowrestricted.
Corrective Actions
Engage blade control handle.
Connect wire to spark plug.
Refer t0i tile engine manual packe!d with your unit.
Refer to the engine manual packed with your unit.
Move throttle lever to FAST or START position.
Carburetornot adjusted prepedy.
Occasional
skip(hesitates)
at highspeed
Idles poody Reset gap to .030=or replace sparkplug•
Excessive
vibration
Mower willnot
mulch grass
Spark pluggap too close.
Carburetoridle mixtureadjustment
improperlyset.
Spark plugfouled, faulty or gaptoo
wide•
Carburetor imprepedy adjusted.
Dirty air cleaner.
Cutting bladeloose or unbalanced.
Bent cuttingblade.
Enginespeed too low.
Wet grass:
Excessivelyhigh grass.
Uneven cut Wheels not positionedcorrectly.
Dull I_ade.
Fill tankwith clean fresh gasoline.Fuelwillnot lastoverthirty
days unlesse fuel stabilizer isused.
Clean fuel line.
Clean, adjust gap or replace.
Refer to the engine manual packedwithyour unit.
Move throttle lever to FAST position.
Connect and tighten spark plugwire.Check sparkplugfur
fouling• i
Clean fuel line;fill tank withclean, freshgasoline.Fuel will
not last overthirtydays unless a fuelstabilizer is added•
Clear vent orthreads or replace.
Drain fubltank. Refill with freshfuel.
Refer td the engine manual packed withyour unit.
Refer to the engine manual packed withyour unit.
Fill crankcasewith proper oil.
Refer to the engine manual packed withyour unit.
Stop engineand disconnect sparkplugwire. Removeblower
housingand clean.
Refer to the engine manual packed withyour unitor see an
authorized service dealer.*
Adjustgap to .030".
Refer to the engine manual packed withyour unit,
Refer to the engine manual packedwithyour unit•
Refer to the engine manuel packedwithyour unit.
Tighten bladeand adapter. Balanceblade.
See an authorizedservice dealer.
Set throttle between 3/4 and fullthrottle.
Do not mow when grass iswet;wait untillatertocut.
Mow onceat a high cutting height,then mow againat
desired heightor make a narrowercuttingswath(1/2 width).
Place all fourwheels insame heightposition.
Sharpen dr replace blade.
Note: For repairs beyond the minor adjustments above, coi_tact your local authorized service dealer.
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