What's the reason for a normally functioning fuel injector not spraying fuel?
3 Answers
There are many reasons why a fuel injector may not spray fuel: insufficient fuel, damaged fuel pump, faulty high-pressure fuel pump, clogged fuel injector, leaking fuel pipe connector, etc., all of which can cause the fuel injector to malfunction. As the supply terminal in the engine's fuel supply system, the fuel injector's role is to inject fuel into the cylinder in a timely, measured manner and at a certain pressure. Here are some solutions for a fuel injector not spraying fuel: 1. Check if the fuel injector has positive voltage, as the computer controls the negative line of the fuel injector. If the injector has positive voltage but no negative signal, and there is currently high voltage, then the computer needs to be repaired. 2. For a clogged fuel injector, use a cleaning needle to unclog it, followed by thorough cleaning. Poor contact between the large flat surface of the needle valve body and the injector body's flat surface, or significant wear on the needle valve's cylindrical surface. 3. If there is poor contact between the large flat surface of the needle valve body and the injector body's flat surface, apply chromium oxide on a flat plate and perform a figure-eight grinding motion. 4. If the needle valve's cylindrical surface is significantly worn, replace the needle valve pair as a set. If the fuel pump is damaged, the fuel transfer pump needs to be inspected and repaired.
If the fuel injector appears normal but fails to deliver fuel, I believe the issue likely lies within the fuel system itself. Firstly, a faulty fuel pump—if there's no humming sound after engine startup, it means oil pressure isn't reaching the injector. Clogged fuel filters are also common, especially in vehicles with long intervals between maintenance, where blocked fuel lines prevent fuel flow. On the electrical side, oxidized, loose, or disconnected wiring connectors at the injector, or a malfunctioning relay failing to switch, can all result in no signal control. The ECU control module might have bugs, possibly due to erroneous sensor signals like a faulty throttle position sensor. Additionally, mechanical sticking of the injector—caused by excessive carbon buildup or aging seals—can prevent fuel spraying. If you experience hard starts or unstable idling, don’t take it lightly; promptly visit a repair shop for professional diagnostics instead of risking DIY fixes that could worsen the situation. Regular injector cleaning and filter replacements can significantly reduce such issues, fostering good habits that save both hassle and money.
From my experience tinkering with cars, troubleshooting a fuel injector that's not spraying requires a step-by-step approach. First, check the fuel pump—listen for its operation when turning the ignition; no sound indicates it's faulty or the fuse is blown. The fuel filter is in the fuel line; if clogged, insufficient fuel pressure will cause the injector to fail. Then inspect the fuel injector's wiring connections—older cars are prone to poor contact or corrosion/rust leading to no power. The relay in the fuse box can be tested by swapping or replacing it. ECU failure is rare but possible; using a diagnostic tool to read error codes is the fastest way to pinpoint issues. If the injector is internally stuck, a professional cleaner flush might help. Always disconnect the battery before working to prevent short circuits—safety comes first. Regularly use high-quality fuel and invest in periodic injector maintenance—it's worth the cost.
