The Complete Small Engine Troubleshooting Flowchart You Can Print and Use

Print this. Post it on your equipment. Follow step by step. You'll diagnose 90% of engine problems without calling anyone.

Does Engine Turn Over?

If no: piston stuck. Pull cord hard five times. If still doesn't move, engine seized. Bring it in. If yes: move to spark test.

Does Spark Plug Have Spark?

Remove spark plug. Hold against cylinder head. Pull cord. See spark jump? If no, replace spark plug ($5-15). If still no spark, ignition coil bad ($80-150).

Is Fuel Getting to Carburetor?

Disconnect fuel line. Turn petcock to on. Does fuel drip? If no, tank empty or fuel line clogged. If yes, move next.

Is Carburetor Flooded?

Remove spark plug. Tip wet with fuel? If yes, pull cord 10 times to clear. Reinstall fresh spark plug. Try starting. If happens again, carburetor needs cleaning ($60-100). If plug dry: carburetor clogged. Bring it in ($60-120).

Engine Fires But Stalls?

Check choke. Cold needs ON. Warm needs OFF. If correct, mixture wrong. Bring it in ($35-50).

Runs Rough Or Dies Under Load?

Replace spark plug ($5-15). Replace air filter ($15-30). Replace fuel filter ($10-20). Add fresh fuel ($0). If still rough, carburetor cleaning ($60-120).

Four Quick Fixes (Solve 75%)

1. Replace spark plug. 2. Replace air filter. 3. Replace fuel filter. 4. Add fresh fuel. Do these before calling technician. If still won't start: professional diagnostic ($35) uncovers carburetor clog, ignition coil bad, fuel pump dead, or compression loss.

Call 301-519-9274.

About the Author

Henry Bockman diagnosed thousands of small engines over 37 years.