Ignition System Problems:
* Ignition Coil: This is a very common culprit. The coil generates the high voltage needed to fire the plugs. A failing coil can cause misfires or no spark at all, sometimes affecting one or more cylinders.
* Ignition Control Module (ICM): This module controls the firing sequence of the coil. A faulty ICM can prevent the coil from receiving the signal it needs to fire. (The location of the ICM varies slightly by engine; consult your owner's manual or a repair manual.)
* Ignition Wires (Spark Plug Wires): These wires carry the high voltage from the coil to the plugs. Cracked, frayed, or corroded wires can prevent spark from reaching the plugs. Check for damage, especially near the distributor cap and spark plug ends.
* Distributor Cap and Rotor (if equipped): If your engine has a distributor, the cap and rotor distribute the high voltage to the correct cylinder. Cracks, carbon buildup, or corrosion in either component can interrupt the spark.
* Crankshaft Position Sensor (CKP Sensor): This sensor tells the computer the position of the crankshaft, which is crucial for timing the spark. A faulty CKP sensor will prevent the computer from sending the signal to fire the coil.
* Camshaft Position Sensor (CMP Sensor): Similar to the CKP sensor, a faulty CMP sensor can disrupt the timing and prevent sparking.
Other Potential Causes:
* Ignition Switch: A faulty ignition switch might not be supplying power to the ignition system.
* Fuses and Relays: Check the fuses and relays related to the ignition system. A blown fuse or a bad relay can interrupt the power flow.
* Computer (PCM): Though less common, a faulty Powertrain Control Module (PCM) can cause ignition problems. This is usually diagnosed by a mechanic using diagnostic equipment.
* Spark Plugs Themselves: While they should *be* the source of the spark, worn-out, fouled, or damaged spark plugs can also prevent firing. However, if *none* are firing, this is less likely to be the sole cause.
* Low Fuel Pressure: The engine needs fuel to ignite, so insufficient fuel pressure can prevent proper combustion.
Troubleshooting Steps (in order of increasing complexity):
1. Visual Inspection: Start by visually inspecting the ignition wires, distributor cap and rotor (if equipped), and spark plugs. Look for any obvious signs of damage or corrosion.
2. Check for Spark: Use a spark tester or even a spare spark plug wired to a good ground to check if you're getting spark from the coil. This helps isolate the problem to the coil or something further upstream.
3. Check Fuses and Relays: Locate and check the fuses and relays associated with the ignition system.
4. Test the Ignition Coil: There are several ways to test the coil, but it's usually best done with a multimeter or a dedicated coil tester.
5. Consult a Repair Manual: A repair manual specific to your 1991 Buick Park Avenue will provide detailed diagrams, testing procedures, and troubleshooting guides.
Important Note: Working on the ignition system involves high voltage that can be dangerous. If you're not comfortable working with electricity, it's best to take your car to a qualified mechanic. Incorrect diagnosis and repair can lead to further damage.
