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What are most likely causes for 1987 jeep Cherokee 4.0 engine to not have spark but yet the turns over fine?

1. Faulty Ignition Coil: The ignition coil is responsible for generating the high voltage needed to create a spark in the spark plugs. If the ignition coil is faulty or has a weak connection, it may not be able to produce enough voltage, resulting in no spark. Check the ignition coil for any cracks or damage, and make sure the connections are tight.

2. Distributor Cap and Rotor: The distributor cap and rotor work together to distribute the high voltage from the ignition coil to the appropriate spark plugs. If either the cap or rotor is cracked, damaged, or has worn-out contacts, it can disrupt the spark delivery, leading to a no-spark condition. Inspect the distributor cap and rotor for damage, and replace them if necessary.

3. Spark Plugs: Worn-out or fouled spark plugs can also prevent the engine from producing a spark. Check the spark plugs for signs of wear, such as eroded electrodes or carbon buildup. If the spark plugs are worn out or damaged, replace them with new ones.

4. Spark Plug Wires: The spark plug wires carry the high voltage from the distributor to the spark plugs. If the spark plug wires are damaged, cracked, or have poor connections, they may not be able to conduct the voltage properly, resulting in no spark. Inspect the spark plug wires for damage, and replace any that are faulty.

5. Crankshaft Position Sensor: The crankshaft position sensor (CKP) provides the engine control module (ECM) with information about the position and speed of the crankshaft. If the CKP sensor is faulty or has a poor connection, the ECM may not be able to properly control the ignition timing, leading to a no-spark condition. Check the CKP sensor for damage, and make sure the connections are secure.

6. Ignition Control Module: The ignition control module (ICM) is responsible for controlling the ignition timing and spark delivery. If the ICM is faulty or has a poor connection, it may not be able to properly control the ignition system, resulting in no spark. Check the ICM for damage, and make sure the connections are secure.