* Battery: This is the most common culprit. A dead or weak battery will prevent the starter motor from engaging. Test the battery voltage with a multimeter. It should be around 12.6V when fully charged. If low, charge it or replace it. Also check the battery cables for corrosion and loose connections.
* Starter Motor: The starter motor itself could be faulty. This requires more advanced diagnostics, potentially including testing the starter relay and solenoid. A clicking sound when you turn the key often indicates a failing starter or related wiring problem.
* Starter Solenoid: This is an electromagnetic switch that connects the battery to the starter motor. A faulty solenoid will prevent the starter from receiving power. Often it manifests as a clicking sound.
* Ignition Switch: A worn or damaged ignition switch may not be sending power to the starter circuit. This is less common but possible.
* Neutral Safety Switch (NSS): Automatic transmissions have a neutral safety switch that prevents starting unless the gear selector is in Park or Neutral. A faulty NSS will prevent starting even if the transmission is in the correct position.
* Wiring: Corrosion, loose connections, or broken wires in the starting circuit can interrupt the power flow. Inspect the wiring harness, especially around the battery, starter, and ignition switch.
* Security System (if equipped): Some 1990 Corvettes might have aftermarket or factory security systems that could be preventing starting.
If the engine cranks but won't start, the problems shift towards:
* Fuel System: No fuel pump prime, clogged fuel filter, faulty fuel injectors, or a low fuel level are all possibilities.
* Ignition System: Problems with the distributor, ignition coil, spark plugs, or wires can prevent ignition.
* Sensors: Various sensors (crankshaft position sensor, camshaft position sensor, etc.) provide information the engine needs to start. A faulty sensor can prevent the engine from starting.
Troubleshooting Steps (No-Crank):
1. Check the battery and cables.
2. Listen for clicking sounds. This can pinpoint the solenoid or starter.
3. Test the voltage at the starter motor terminal when trying to start.
4. Check fuses and relays associated with the starter circuit.
5. If you have basic electrical knowledge, you might want to test the starter motor directly using jumper cables and a power source (BE CAREFUL!).
It's recommended to get help from a mechanic experienced with older Corvettes, especially if you are not comfortable with automotive electrical systems. They have the tools and expertise to diagnose the problem accurately and efficiently.
