1. Fuel System Issues:
* Fuel Pump: A faulty fuel pump can prevent fuel from reaching the engine. Listen for the fuel pump humming when you turn the key to the "on" position (not start). If you don't hear it, the pump might be dead.
* Fuel Filter: A clogged fuel filter can restrict fuel flow. It's a relatively cheap and easy part to replace.
* Fuel Lines: Make sure there are no leaks or obstructions in the fuel lines between the tank and the engine.
* Fuel Injectors: Clogged or malfunctioning fuel injectors can prevent fuel from entering the cylinders.
2. Ignition System Issues:
* Distributor (if applicable): On older cars like your Mazda 626, the distributor could be faulty. It's responsible for directing spark to the spark plugs in the correct order.
* Ignition Coils: These components generate the spark that ignites the air-fuel mixture. A faulty coil can cause misfires or a complete lack of spark.
* Spark Plug Wires: While you replaced the wires, ensure they are properly connected and that there are no cracks or damaged insulation.
3. Engine Mechanical Issues:
* Compression: A lack of compression in the cylinders could be due to a blown head gasket, worn valves, or damaged pistons.
* Timing: The engine timing must be set correctly for the spark to occur at the right moment. If it's off, the car won't start.
Troubleshooting Steps:
1. Check for Spark: Remove a spark plug wire, hold it near a grounded metal part (with the engine off), and have someone crank the engine. You should see a spark jump between the wire and the metal. If not, there's an issue with the ignition system.
2. Check for Fuel Delivery: If you have a fuel pressure gauge, connect it to the fuel rail and check the pressure while cranking the engine. If there's no pressure, the fuel pump is likely the culprit.
3. Listen for Engine Noises: Pay attention to any unusual sounds from the engine while cranking. Clicking sounds could indicate a faulty starter or compression issue.
4. Check for Codes: Use an OBD-II code reader to scan the car for any stored error codes. These can provide valuable information about the problem.
Important Note:
* If you're not comfortable diagnosing and repairing car problems yourself, it's best to take it to a qualified mechanic. They have the tools and expertise to quickly identify and fix the issue.
* Be careful working around the ignition system, as it can be dangerous to deal with high voltage.
I hope this helps. Good luck!
