MTD 420 Series Lawn Mower User Manual


 
12
For repairs beyond
the minor adjustments
listed here, contact
an authorized service
dealer.
6
Trouble
Shooting
Cause
Problem
Remedy
Engine fails to start
Engine runs erratic
1. Connect and tighten spark plug wire.
2. Clean fuel line; fill tank with clean,
fresh gasoline.
3. Clear vent.
4. Drain fuel tank. Refill with fresh fuel.
5. Refer to engine manual.
6. Refer to engine manual.
1. Spark plug wire loose.
2. Blocked fuel line or stale fuel.
3. Vent in gas cap plugged.
4. Water or dirt in fuel system.
5. Dirty air cleaner.
6. Carburetor out of adjustment.
Engine overheats
1. Fill crankcase with proper oil.
2. Remove blower housing and clean.
3. Refer to engine manual.
1. Engine oil level low.
2. Air flow restricted.
3. Carburetor not adjusted properly.
Occasional skips
(hesitates) at high speed
1. Adjust gap to .030-inch.
2. Refer to engine manual.
1. Spark plug gap too close.
2. Carburetor idle mixture adjustment
improperly set.
Idles poorly
1. Reset gap to .030-inch or replace
spark plug.
2. Refer to engine manual.
3. Refer to engine manual.
1. Spark plug fouled, faulty or gap too wide.
2. Carburetor improperly adjusted.
3. Dirty air cleaner.
Mower will not mulch grass
1. Do not mow when grass is wet; wait
until later to cut.
2. Mow once at a high cutting height,
then mow again at desired height or
make a narrower cutting path.
3. Sharpen or replace blade.
1. Wet grass.
2. Excessively high grass.
3. Dull blade.
Uneven cut
1. Place all four wheels in same
height position.
2. Sharpen or replace blade.
1. Wheels not positioned correctly.
2. Dull blade.
Excessive Vibration
1. Cutting blade loose or unbalanced.
2. Bent cutting blade.
1. Tighten blade and adapter. Balance
blade.
2. See an authorized service dealer.
NOTE: Specifications are
subject to change without
notification or obligation.
Images my not reflect your
exact model and are for
reference purposes only.
1. Blade control disengaged.
2. Spark plug wire disconnected.
3. Fuel tank empty or stale fuel.
4. Engine not primed (if equipped with
primer).
5. Faulty spark plug.
6. Blocked fuel line.
7. Engine flooded.
8. Fuel valve (if equipped) closed.
9. Engine not choked (if equipped w/choke).
1. Engage blade control.
2. Connect wire to spark plug.
3. Fill tank with clean, fresh gasoline.
4. Prime engine as instructed in “Operat
-
ing Your Lawn Mower”.
5. Clean, adjust gap, or replace.
6. Clean fuel line.
7. Wait a few minutes to restart, but do
not prime.
8. Open fuel valve. See engine manual.
9. Choke engine. See engine manual.