What is the reason for a diesel injector not spraying fuel at 5V voltage?
2 Answers
Injector drive voltage needs to be between 11V-13V to function properly. Precursors of injector damage: 1. Engine vibration: When a vehicle's fuel injector is damaged and fuel injection becomes uneven, the engine may exhibit symptoms like operational vibration during operation. 2. Decreased power and increased fuel consumption: As the injector deteriorates, fuel injection quantity and pressure cannot be guaranteed, leading to symptoms of reduced vehicle power and increased fuel consumption. 3. Increased exhaust emissions pollution: Faults in the engine injector will inevitably affect the mixing and combustion of the combustible gas mixture, thereby increasing vehicle exhaust emissions pollutants. 4. Difficulty starting or even stalling: If the injector is severely damaged, the vehicle may experience difficulty starting, or even sudden stalling while driving.
As a long-time enthusiast studying diesel vehicles, I know that when the fuel injector shows 5V but doesn't spray fuel, the issue could lie in several areas. This 5V voltage typically indicates a sensor reference voltage or normal ECU input signal, not the power voltage driving the injector. Fuel injectors require high-current pulses to operate, usually 12V or higher system voltage. If a steady 5V level is measured, it suggests the drive signal may be missing or there's an ECU output failure. Possible causes include burnt injector coils causing increased resistance or short circuits, faulty driver circuit transistors, insufficient fuel pressure due to clogged fuel lines, or incorrect ECU sensor inputs. Once, I encountered a vehicle where crankshaft position sensor signal interference caused the ECU to misjudge and not send fuel injection signals. For troubleshooting, start with the basics: first check if the fuel filter is clogged and ensure the fuel pump pressure is normal; then measure the injector coil resistance with a multimeter—if it shows infinity, replacement is needed; if there's no pulse waveform on the drive line, it could be due to ECU issues or a short circuit in the wiring. Don’t overlook voltage changes at the sensor signal terminals. In summary, timely repairs are crucial to prevent engine damage.
