Common Causes (affecting all or most injectors):
* Fuel Pump Failure: The most common cause is a malfunctioning fuel pump. No fuel pressure means no fuel to the injectors. Check fuel pressure using a gauge.
* Clogged Fuel Filter: A clogged filter restricts fuel flow, starving the injectors. Replace the fuel filter.
* Bad Fuel Pressure Regulator: This regulator maintains the correct fuel pressure. A faulty one can lead to either too low or too high pressure, both problematic for injectors.
* Ignition System Problems: While seemingly unrelated, a faulty ignition system (crankshaft position sensor, coil, distributor) can prevent the engine from running, making it *seem* like a fuel injector issue.
* PCM (Powertrain Control Module) Failure: The PCM controls the injectors. A faulty PCM can stop the injectors from firing, though this is less common than other issues. This requires diagnostics.
* Low Battery Voltage/Poor Ground: Insufficient power can prevent proper injector operation. Check the battery voltage and ground connections.
* Fuel Pump Relay: This relay switches power to the fuel pump. A bad relay prevents the pump from working.
* Wiring Issues: Corroded, damaged, or disconnected wires to the injectors or fuel pump can interrupt the circuit. Inspect the wiring carefully.
Causes Affecting Individual Injectors:
* Clogged Injector: An injector can become clogged with debris, preventing proper fuel spraying. Cleaning or replacing the affected injector might resolve this.
* Faulty Injector: An injector itself can fail internally. This usually requires injector testing or replacement.
* Wiring Harness Issues (Individual Injector): A problem with the wiring to a specific injector.
Troubleshooting Steps:
1. Check for Fuel Pressure: This is the *first* thing to do. Low or no pressure points to the fuel pump, filter, or regulator.
2. Inspect the Fuel Filter: Replace it as a preventative measure even if pressure seems okay.
3. Check for Spark: Ensure the ignition system is functioning correctly.
4. Visual Inspection: Examine the wiring harness for any damage, corrosion, or loose connections.
5. OBD-II Diagnostic: If your vehicle has an OBD-II port, get the codes read. This can pinpoint the problem area.
6. Injector Testing: If the problem is intermittent or only affects some injectors, individual injector testing is necessary. This requires specialized tools.
Important Note: Working on fuel systems involves working with flammable materials. Take necessary safety precautions. If you are not comfortable performing these checks yourself, take your vehicle to a qualified mechanic.
