Engine won't crank when trying to start
- Loose or oxidized battery terminal connections (Section 1).
- The battery is empty or defective (Section 1 or 12).
- Broken, loose or disconnected wiring in the starter circuit (Section 12).
- Faulty traction relay or starter switch (Section 12).
- Starter motor defective (Section 12).
- Worn or broken flywheel ring teeth or electric starter gears (Section 2 or 12).
- Broken or disconnected engine ground strap (Section 2or 12).
Engine cranks but won't start
- Empty fuel tank.
- Low battery (engine spins slowly) (Section 12).
- Loose or oxidized battery terminal connections (Section 1).
- Shunted or damaged ignition components (Section 1 or 5).
- Broken, loose or disconnected wiring in the ignition circuit (Section 1 or 5).
- Spark plugs worn out or defective, electrode gap set incorrectly (Section 1).
- Throttle mechanism stuck, misadjusted, or defective (Section 4).
- Mechanical damage (e.g. camshaft drive) (Section 2).
Cold engine difficult to start
- Low battery (Section 12).
- Loose or oxidized battery terminal connections (Section 1).
- Spark plugs worn out or defective, electrode gap set incorrectly (Section 1).
- The damper mechanism is jammed, incorrectly adjusted or defective (Section 4).
- Another malfunction in the ignition system (Section 1 and 5).
- Low compression in the engine cylinder (Section 2).
Warm engine difficult to start
- Dirty or clogged air filter element (Section 1).
- Throttle mechanism stuck, misadjusted, or defective (Section 4).
- Carburetor float chamber flooding (Section 4).
- Low compression in the engine cylinder (Section 2).
Starter makes noise or engages roughly
- Worn or broken teeth on flywheel ring or electric starter gear (Section 2 or 12).
- Loose or missing starter mounting bolts (Section 12).
- Worn or damaged internal starter components (Section 12).
Engine starts, but immediately stalls
- Insufficient amount of fuel enters the carburetor (Section 4).
- Loose or defective wiring in the ignition circuit (Section 1 or 5).
- Vacuum leak in carburetor or intake manifold (Section 4).
- Blocked jets or internal carburetor passages (Section 4).
Engine runs erratically at idle
- Idle speed and/or mixture incorrectly adjusted (Section 1).
- Clogged air filter element (Section 1).
- Vacuum leak in carburetor, intake manifold, or related hoses (Section 4).
- Spark plugs worn out or defective, electrode gap set incorrectly (Section 1).
- Valve clearances incorrectly adjusted (Section 1).
- Unequal or low compression in the engine cylinders (Section 2).
- Camshaft cams worn out (Section 2).
- Excessively worn drive chain (Section 2).
Ignition misfires at idle
- Spark plugs worn out or defective, electrode gap set incorrectly (Section 1).
- Defective high voltage spark plug wiring (Section 1).
- Incorrectly adjusted idle mixture (Section 1).
- Wrong ignition timing (Section 1).
- Vacuum leak in carburetor, intake manifold, or related hoses (Section 4).
- Distributor breaker cover cracked or otherwise damaged (Section 1).
- Valve clearances incorrectly adjusted (Section 1).
- Unequal or low compression in the engine cylinders (Section 2).
- Disconnected, loose or punctured crankcase breather hose (Section 1 or 4).
Misfires in all driving modes
- Blocked jets or internal carburetor passages (Section 4).
- Carburetor misadjusted or worn (Section 1 or 4).
- Fuel filter blocked (Section 1).
- Faulty fuel priming pump, or low supply pressure (Section 4).
- Drain hole in the fuel tank is blocked or the flow area of the fuel lines has decreased (Section 4).
- Vacuum leak in carburetor, intake manifold, or related hoses (Section 4).
- Spark plugs worn out or defective, electrode gap set incorrectly (Section 1).
- Damaged high voltage spark plug wiring (Section 1).
- Distributor breaker cover cracked or otherwise damaged (Section 1).
- Defective ignition coil (Section 5).
- Unequal or low compression in the engine cylinders (Section 2).
Engine fails when pressing gas pedal
- Spark plugs worn out or defective, electrode gap set incorrectly (Section 1).
- Faulty carburetor accelerator pump (Section 4).
- Blocked jets or internal carburetor passages (Section 4).
- Vacuum leak in carburetor, intake manifold, or related hoses (Section 4).
- Carburetor misadjusted or worn (Section 1 or 4).
Engine stalls
- Idle speed and/or mixture incorrectly adjusted (Section 1).
- Blocked jets or internal carburetor passages (Section 4).
- Vacuum leak in carburetor, intake manifold, or related hoses (Section 4).
- Fuel filter blocked (Section 1).
- Faulty fuel priming pump, or low supply pressure (Section 4).
- The drain hole in the fuel tank is blocked or the flow area of the fuel lines has decreased (Section 4).
The engine does not develop full power
- Wrong ignition timing (Section 1).
- Carburetor misadjusted or worn (Section 1 or 4)
- Drive chain incorrectly installed (Section 2).
- Fuel filter blocked (Section 1).
- Faulty fuel priming pump, or low supply pressure (Section 4).
- Unequal or low compression in the engine cylinders (Section 2).
- Spark plugs worn out or defective, electrode gap set incorrectly (Section 1).
- Vacuum leak in carburetor, intake manifold, or related hoses (Section 4).
- Wheel braking (Section 1 or 9).
- Clutch slip (Section 6).
The engine backfires
- Incorrect ignition timing (Section 1).
- Drive chain incorrectly installed (Section 2).
- Carburetor misadjusted or worn (Section 1 or 4).
- Vacuum leak in carburetor, intake manifold, or related hoses (Section 4).
The oil pressure warning lamp lights up when the engine is running
- Low oil level or wrong grade (Section 1).
- Defective oil pressure sensor (Section 2).
- Worn crankshaft bearings and/or oil pump (Section 2).
- High engine operating temperature (Section 3).
- Defective oil pump bypass valve (Section 2).
- Clogged oil pump intake strainer (Section 2).
Engine running after ignition off
- Excessively high idle speed (Section 1).
- Excessive soot in the engine (Section 2).
- High engine operating temperature (Section 3).
Noises in the engine
Pre-ignition, detonation under acceleration or under load
- Incorrect ignition timing (Section 1).
- Wrong grade of fuel (Section 4).
- Vacuum leak in carburetor, intake manifold, or related hoses (Section 4).
- Excessive soot in the engine (Section 2).
- Worn or damaged distributor or other component of the ignition system (Section 1 or 5).
- Carburetor misadjusted or worn (Section 1 or 4).
Whistling and hissing are heard
- Leak from intake manifold or carburetor gasket (Section 4).
- Leakage at exhaust manifold gasket or at pipe-to-manifold junctions (Section 1 or 4).
- Vacuum hose leak (Section 4 or 9).
- Burnt cylinder head gasket (Section 2).
You hear a knock or rattle
- Incorrect valve clearances (Section 1).
- Worn valve train or camshaft (Section 2)
- Worn drive chain (Section 2).
- Auxiliary components damaged (cooling system pump, generator, etc.) (Section 3 or 12).
Muffled knock
- Worn connecting rod bearings (strong rumble, may weaken under load) (Section 2).
- Worn main bearings (rattling or rattling sound, may increase under load) (Section 2).
- Piston knock (more noticeable when running a cold engine) (Section 2).
- Auxiliary components damaged (generator, cooling system pump, etc.) (Section 3 or 12).