* Compression: Lack of sufficient compression in one or more cylinders prevents the fuel-air mixture from igniting properly, even with spark. A compression test is crucial here. Low compression can be caused by worn piston rings, a blown head gasket, or valve issues.
* Crank Sensor/Crankshaft Position Sensor (CKP): Even though you have spark, a faulty CKP sensor can prevent the engine from starting. This sensor tells the computer the crankshaft's position, which is essential for proper ignition timing. A bad signal can result in no combustion even with fuel and spark.
* Cam Sensor/Camshaft Position Sensor (CMP): Similar to the CKP sensor, a faulty CMP sensor provides incorrect information about the camshaft's position, disrupting the timing of the fuel injection and ignition.
* Fuel Pressure: While you say you have fuel *to* the injectors, the *pressure* might be insufficient. A fuel pressure test is necessary to confirm that the injectors are receiving fuel at the correct pressure. A weak fuel pump is a common culprit.
* Air intake system leaks: A large leak in the air intake system after the mass airflow sensor (MAF) can cause a lean condition, preventing combustion even with spark and fuel.
* Ignition Control Module (ICM): This component controls the ignition system. A faulty ICM can cause intermittent or complete failure of the spark, even if the spark plugs and wires are fine. (While you say you have spark, ensure it's strong and consistent across all cylinders)
* ECU (Engine Control Unit): Though less likely, a problem within the ECU itself could prevent the engine from starting, even if all other components appear to be working. This is usually diagnosed by a professional with specialized equipment.
Troubleshooting Steps:
1. Compression Test: This is the most important first step. A low compression reading in one or more cylinders points to a serious mechanical issue.
2. Fuel Pressure Test: Check the fuel pressure to ensure it's within the manufacturer's specifications.
3. Check for Air Leaks: Carefully inspect all hoses and connections in the air intake system for leaks.
4. Inspect CKP and CMP Sensors: Check the sensors for damage or corrosion. You may need a multimeter to test their output signal (consult a repair manual for specifics).
5. Verify Strong Spark: Ensure a strong and consistent spark is present at each spark plug. Weak spark can be caused by worn plugs, wires, or the ignition coil.
If you're not comfortable performing these tests yourself, take your Dodge Colt to a qualified mechanic for diagnosis and repair. Attempting to troubleshoot further without proper tools and knowledge can lead to additional damage. A professional scan tool can also help diagnose issues related to sensors and the ECU.
