Tecumseh AH520 - Engine Troubleshooting; 2-Cycle Engine Troubleshooting Chart and Knocks

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TROUBLESHOOTING
2 CYCLE ENGINE TROUBLESHOOTING CHART
Cause Remedy and Reference
ENGINE FAILS TO START OR STARTS WITH DIFFICULTY
No fuel in tank Fill tank with clean, fresh fuel with correct oil ratio.
Fuel shut-off valve closed Open valve.
Obstructed fuel line Clean fuel screen and line. If necessary, remove
and clean carburetor.
Tank cap vent obstructed Open vent in fuel tank cap or replace cap.
Water in fuel Drain tank. Clean carburetor and fuel lines. Dry
spark plug points. Fill tank with clean, fresh fuel.
Engine overchoked Close fuel shut-off and pull starter until engine starts.
Reopen fuel shutoff for normal fuel flow immediately
after engine starts.
Improper carburetor adjustment Adjust carburetor.
Loose or defective magneto wiring Check magneto wiring for shorts or grounds; repair
if necessary.
Sheared or incorrect flywheel key or adapter sleeve Replace with correct key or adapter sleeve.
Faulty Magneto Check timing, point gap, and if necessary, overhaul
magneto.
Spark plug fouled Clean and regap spark plug.
Crankcase seals and/or gaskets leaking Replace seals and/or gaskets.
Spark plug porcelain cracked Replace spark plug.
Poor Compression Overhaul engine.
Exhaust ports plugged Clean exhaust ports
ENGINE KNOCKS
Carbon in combustion chamber Remove cylinder head or cylinder and clean carbon
from head and piston.
Loose or worn connecting rod Replace connecting rod.
Loose flywheel Check flywheel key and keyway; replace parts if
necessary. Tighten flywheel nut to proper torque.
Worn cylinder Replace cylinder.
Improper magneto timing Time magneto.