1. Late fuel supply (injection timing advance angle is small); difficult engine starting; in idle mode the engine runs intermittently and smokes (gray smoke), under load the engine runs smoothly, but smokes (black smoke); reduced engine power and responsiveness; increased fuel consumption.
2. Early fuel supply (injection advance angle is large); the engine runs in a "hard" mode, with metallic knocks (especially at low engine crankshaft speeds); exhaust smoke is barely noticeable at idle, but increases with increasing load (black smoke).
3. Clogged fuel filters: uneven engine operation in all modes; uneven exhaust; reduced engine power and responsiveness.
4. The injector does not work: the engine runs unevenly; when a non-working injector is switched off, the engine's operating characteristics and exhaust smoke do not change.
5. Wear or coking of injector nozzles: increased exhaust smoke; difficult engine starting; reduced power.
6. Presence of air in the system or accumulation of a large amount of water in the fuel filter: the engine does not start.
7. Malfunction of the fuel shut-off solenoid valve: the engine does not start (the valve does not turn on due to a fault in the power supply circuit or is stuck in the closed position) or does not stall after turning off the ignition (valve stuck open).
8. Malfunction of preheating systems: the engine does not start (the fast warm-up stage does not work) or it works unstably and stalls immediately after starting (the warm-up stage does not work after starting).
9. Incorrect adjustment of the amount of fuel supplied in idle mode or in maximum speed mode: the engine crankshaft speed does not correspond to the selected engine operating mode (position of the fuel pedal) with all the ensuing consequences (unstable operation at idle or at maximum speed, loss of engine power and responsiveness, etc.).
[The original can be read on the website nissanbook.ru]