What Causes Fuel Injector Failure?
2 Answers
Fuel injector failure can be caused by the following reasons: 1. Poor fuel atomization: When the injection pressure is too low, the injector nozzle is worn or has carbon deposits, or the spring end face is worn or the spring force is reduced, the injector will open prematurely and close late, resulting in poor fuel atomization. 2. Damaged injector return line: When the needle valve pair is severely worn or the fit between the needle valve body and the injector housing is not tight enough, the injector's return fuel volume increases significantly, sometimes reaching 0.1–0.3 kg/h. If the return line is damaged or missing, the return fuel is wasted. 3. Enlarged needle valve nozzle: Due to continuous high-pressure fuel flow erosion, the needle valve nozzle gradually wears out, leading to decreased injection pressure, shorter injection distance, poor diesel atomization, and increased carbon deposits in the cylinder. 4. Needle valve seizure: Water or acidic substances in the diesel can cause the needle valve to rust and stick. If the needle valve sealing cone surface is damaged, combustible gas in the cylinder can also enter the mating surface, forming carbon deposits that cause the needle valve to seize, rendering the injector non-functional and stopping the cylinder. 5. Wear on the needle valve body end face: The needle valve body end face is subjected to frequent reciprocating impacts from the needle valve, which over time forms a concave pit, increasing the needle valve lift and affecting the injector's normal operation. 6. Air leakage and oil seepage at the injector and cylinder head joint: When installing the injector into the cylinder head, carefully remove carbon deposits from the installation hole. The copper gasket must be flat and should not be replaced with asbestos or other materials to prevent poor heat dissipation or sealing failure. 7. Wear on the needle valve and needle valve bore guide surface: The needle valve's frequent reciprocating motion inside the needle valve bore, combined with contamination from diesel impurities, gradually wears the guide surface, increasing the gap or causing scratches. This leads to increased internal leakage in the injector, reduced pressure, decreased fuel injection volume, delayed injection timing, and difficulty starting the diesel engine. 8. Injector dripping: During injector operation, the needle valve body's sealing cone surface is subjected to frequent strong impacts from the needle valve, along with continuous high-pressure fuel flow erosion. Over time, the cone surface develops scratches or spots, losing its sealing ability and causing the injector to drip fuel.
I've been repairing cars for decades, and the common causes of fuel injector failure are impurities in the fuel clogging the injector nozzles or the injectors themselves aging and wearing out severely. Especially with unclean gasoline, excessive carbon buildup can completely block the nozzles, leading to uneven fuel injection, causing severe engine shaking and a sharp increase in fuel consumption. Additionally, electrical issues such as a faulty fuel injection control sensor or poor wiring connections can also cause the fuel injectors to stop working. I once had a customer whose car suddenly stalled while driving, and upon inspection, it turned out the fuel injector connector had come loose. I recommend using high-quality fuel, cleaning the fuel injectors during every maintenance service, and adding some fuel additives to prevent carbon buildup. If your car struggles to accelerate or emits black smoke from the exhaust, don't hesitate—take it to a professional repair shop immediately for diagnosis. Driving under such conditions can easily lead to accidents.
