Fuel System Problems:
* Fuel Pump Failure: The fuel pump might be weak, failing to deliver sufficient fuel to the engine. You might hear the pump prime when you turn the key (a brief whirring sound), but it could be weak or not working consistently.
* Clogged Fuel Filter: A clogged fuel filter restricts fuel flow, preventing enough fuel from reaching the injectors.
* Fuel Injector Issues: One or more fuel injectors could be clogged, malfunctioning, or not receiving the correct signal.
* Low Fuel: Sounds obvious, but make sure you actually have gas in the tank!
* Fuel Pressure Regulator: This regulator maintains the correct fuel pressure. A faulty one can lead to incorrect fuel pressure, hindering combustion.
Ignition System Problems:
* Distributor Cap and Rotor: These parts can wear down, causing poor spark delivery to the spark plugs. Cracks or corrosion are common causes of failure.
* Spark Plugs and Wires: Worn, fouled, or damaged spark plugs or wires can prevent a sufficient spark from reaching the cylinders.
* Ignition Coil: This component generates the high voltage necessary for ignition. A failing coil will result in weak or no spark.
* Ignition Control Module (ICM): This module controls the ignition timing and spark delivery. A faulty ICM can cause intermittent or complete starting failure.
* Crankshaft Position Sensor (CKP) or Cam Position Sensor (CMP): These sensors tell the engine's computer where the crankshaft and camshaft are located. If faulty, the computer can't accurately time the spark.
Other Potential Issues:
* Security System: Some 1995 Rivieras had anti-theft systems. A malfunctioning system could prevent the engine from starting.
* Battery and/or Cables: A weak battery or corroded battery cables can prevent sufficient power from reaching the starter and other components. Test the battery voltage.
* Starter Relay: While the starter cranks, a faulty relay might not be delivering full power to the starter motor.
* Engine Control Module (ECM): A faulty ECM can prevent proper engine operation and starting. This is a less common, but possible, cause.
Troubleshooting Steps:
1. Check the obvious: Ensure the car is in Park (automatic) or Neutral (manual) and that the battery is charged.
2. Listen carefully: Do you hear the fuel pump prime when you turn the key? If not, there's a problem with the fuel pump circuit.
3. Check for Codes: Use an OBD-II scanner to read any diagnostic trouble codes (DTCs) stored in the ECM. These codes will point you to likely culprits.
4. Visual Inspection: Check for obvious signs of damage, corrosion, or loose connections in the engine compartment, particularly around the distributor, spark plugs, and fuel lines.
5. Systematic approach: Begin by checking the simplest things first (fuel, battery, connections), then move towards more complex components (sensors, modules).
If you're not comfortable working on cars yourself, it's best to take your Riviera to a qualified mechanic for diagnosis and repair. The cost of a misdiagnosis can outweigh the cost of professional help.
