Weak compression

High compression

Air lock in fuel system

Poor oil circulation

Low fuel level in tank

Low charged battery

Clogged nozzle

No air in fuel system

Radiator cap blocked

Fuel tank cap vent hole blocked

Oil filter blocked

Oil pump gear worn out

Engine does not start

Engine over heated

High fuel pressure

High oil pressure

Engine seized

High oil pressure

Low oil pressure

Detonation occur