* Crankshaft Position Sensor (CKP): This sensor is crucial. It tells the computer the position of the crankshaft, allowing it to time the spark and fuel injection precisely. A faulty CKP will prevent the engine from starting. This is a high-probability suspect given your description.
* Camshaft Position Sensor (CMP): Similar to the CKP, the CMP sensor tells the computer the position of the camshaft. While less critical for a basic start than the CKP, a faulty CMP can still prevent the engine from running properly and starting can be difficult or impossible.
* Computer (ECU): The Engine Control Unit receives signals from various sensors and controls the fuel injection and ignition timing. A faulty ECU could be misinterpreting signals or failing to send the correct commands. This is less likely but possible. (ECU testing usually requires specialized equipment.)
* Ignition Control Module (ICM): (Sometimes integrated with the distributor on some models) This module controls the ignition system. A problem here could cause intermittent or complete spark failure, even if you've confirmed some spark at the plugs.
* Fuel pressure regulator: While you mentioned fuel delivery, verify that the fuel pressure is correct. A faulty regulator could result in insufficient fuel pressure even if the system is pumping fuel.
* Wiring and Connectors: Check all wiring and connectors related to the ignition and fuel systems. Corrosion, loose connections, or damaged wires can easily disrupt signals and prevent starting. Pay close attention to the wiring harness near the crankshaft and camshaft sensors.
How to proceed:
1. Check the CKP Sensor: This should be your top priority. Locate the CKP sensor (consult a repair manual for the exact location), and visually inspect it for damage. You may need a multimeter to check its output voltage or resistance; consult your repair manual for specifics on testing the sensor.
2. Check the CMP Sensor (if applicable): If the CKP checks out, move on to the CMP sensor and test it similarly.
3. Check Fuel Pressure: Use a fuel pressure gauge to verify that the fuel pressure is within the manufacturer's specifications.
4. Inspect wiring and connectors: Carefully examine all wiring and connectors associated with the ignition and fuel systems for any signs of damage or corrosion.
5. Professional diagnosis: If you're not comfortable performing these tests yourself, or if you've checked these things and the problem persists, take your Geo Storm to a qualified mechanic. They'll have the tools and expertise to diagnose the problem accurately.
A repair manual specific to your 1992 Geo Storm will be invaluable during this process. It will provide diagrams, specifications, and troubleshooting guides. You can find these online (often as PDF downloads) or at auto parts stores. Remember safety first; always disconnect the negative battery terminal before working on any electrical components.
