Listed below are some of the common engine problems or troubles and their possible causes

ENGINE DOES NOT START: possible causes

- Empty fuel tank

- Fuel is old, dirty, or contaminated

- Fuel pump not working

- Fuel supply hose damaged, distorted, or improperly attached

- Inappropriate, clogged, or faulty spark plugs

- Loose plug wires

- Starter motor is not operational

- Battery is undercharged

- Ignition coil not functional

- Broken ignition switch

- Faulty wiring and connection problems in the ignition system



ENGINE STALLS: possible causes

- Fuel supply hose damaged, distorted, or improperly attached

- Fuel tank empty

- Fuel filter is clogged up

- Fuel is old, dirty, or contaminated

- Fuel supply hose damaged, distorted, or improperly attached

- Closed fuel tank vent

- Inoperative, or clogged thermostat

- Wrong engine oil

- Spark plugs defective, wrong, plugged, or incorrect spark-plug gap



ENGINE KNOCKS or DETONATES (PINGING): possible causes

- clogged Carburetor

- Ignition Distributor problems

- plugged fuel Injectors

- Valve timing fails, or faulty

- failed or loose timing belt tensioner

- lean air-to-fuel mixture

- using fuel of lower than recommended Octane Rating

- too high engine compression

- Anti-Knock sensors malfunction

- Engine is too hot

- lack of proper exhaust gas recirculation

- air conditioning compressor fails or ices up

- Carbon deposits in the combustion chamber, pistons, cylinders, valves, or exhaust system lines

- Faulty or defective main crankshaft bearings

- water pump bearing is worn out

- Alternator rotor has worn bearings

- Flywheel is broken or has cracks



ENGINE IDLE IS ROUGH: possible causes

- Carburetor is flooded

- Fuel hose crushed or twisted

- Fuel filter clogged

- Fuel being used is contaminated or old and stale

- Throttle linkage sticking

- Spark plugs defective, wrong, plugged, or incorrect spark-plug gap

- Ignition problems occur in one or more cylinders

- Ignition wires maybe cracking or broken

- improper connection at both distributor cap and spark plugs

- clogged catalytic converter

- exhaust system is restricted or has blockage



ENGINE SPEED IS LOW OR NOT INCREASING: possible causes

- Fuel filter is clogged

- Fuel supply hose incorrectly connected, broken, or twisted

- Fuel is old, dirty, or contaminated

- Spark plugs defective, wrong, plugged, or incorrect spark-plug gap

- Low engine oil level



ENGINE SMOKES: possible causes

- engine is burning oil

- worn or broken piston rings

- worn or damaged cylinders

- worn valve guide or valve guide seals

- engine is burning coolant or transmission fluid

- leaking head gasket

- broken or cracked cylinder head

- Air filter is clogged

- Air/fuel mixture is too rich

- stuck automatic choke in the carburetor

- leaky fuel injector

- fuel pressure is too much



ENGINE OVERHEATING: possible causes

- Overloading

- Water pump failure

- loose water pump impeller

- Clogged water lines

- Defective or clogged Thermostat

- Oil pump is faulty or not functional

- Engine oil level is too low

- Using old, contaminated, or incorrect engine oil

- Using spark plugs with inappropriate heat-range

- low coolant level, coolant leak, or poor coolant circulation

- faulty coolant sensor or air trapped under the sensor

- accumulated deposits in the water jackets

- fan clutch slips or misses

- cooling fan failure

- broken, cracked radiator hose

- ruptured or broken radiator cap

- poor airflow through the radiator

- Radiator is poor or inefficient