Section9: Troubleshooting - Troy-Bilt 979 Operator's Manual

SECTION9: TROUBLESHOOTING
Problem Cause
Engine fails to start
Engine runs erratic
1. Blade control handle disengaged.
2. Start control button not depressed.
3. Spark plug wire disconnected.
4. Safety key not in run position
5. Fuel tank empty or stale fuel.
6. Blocked fuel line.
7. Faulty spark plug.
8. Engine flooded
9. Self Starter already de-energized.
1. Spark plug wire loose.
2. Blocked fuel line or stale fuel.
.
4.
5.
6.
Engine overheats 1.
2.
3.
Occasional skip (hesitates 1.
at high speed
Vent in gas plugged.
Water or dirt in fuel system.
Dirty air cleaner.
Carburetor out of adjustment.
Engine oil level low.
Air flow restricted.
Carburetor not adjusted properly.
Spark plug gap too close,
Remedy
1. Engage blade control handle.
2. Depress starter control button
3. Connect wire to spark plug.
4. Place safety key in run position.
5. Fill tank with clean, fresh gasoline.
6. Clean fuel line.
7. Clean, adjust gap, or replace.
8. Wait a few minutes to start.
9. Use recoil starter to start engine.
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. Clean air cleaner.
6. Adjust carburetor.
1. Fill crankcase with proper oil.
2. Remove blower housing and clean.
3. Adjust carburetor.
1. Adjust gap to .030".
Idles poorly 1. Spark plug fouled, faulty or gap too 1. Reset gap to .030" or replace spark
wide. plug.
2. Carburetor improperly adjusted. 2. Adjust carburetor.
3. Dirty air cleaner. 3. Clean air cleaner.
Excessive vibration 1. Cutting blade loose or unbalanced. 1. Tighten blade and adapter. Balance
blade.
2. Bent cutting blade. 2. Replace blade.
Mower wilt not mulch gras,, 1. Wet grass. 1. Do not mow when grass is wet; wait
until later to cut.
2. Excessively high grass. 2. Mow once at a high cutting height, then
mow again at desired height or make a
narrower cutting path.
3. Dull blade. 3. Sharpen or replace blade.
Uneven cut 1. Wheels not positioned correctly. 1. Place all four wheels in same height
position.
2. Dull blade. 2. Sharpen or replace blade.
Wheels wilt not propel 1. Belt not installed properly. 1. Check belt for proper pulley installation
and movement.
2. Debris clogging drive operation. 2. Clean out debris with engine off.
NOTE: For repairs beyond the minor adjustments listed above, contact your nearest authorized service dealer.
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