* Crankshaft Position Sensor (CKP): This sensor is crucial. It tells the computer the engine's rotational position, which is essential for timing the spark and fuel injection. A faulty CKP will prevent both. This is a very common cause of this type of no-start condition.
* Cam Position Sensor (CMP): Similar to the CKP, a bad CMP will disrupt ignition and fuel injection timing. Some Stealth engines use this sensor.
* Computer (PCM/ECM): The Powertrain Control Module (PCM) or Engine Control Module (ECM) – the car's "brain" – controls both ignition and fuel injection. A faulty PCM could be the primary source of the problem. This requires diagnostics to confirm.
* Ignition Control Module (ICM): While less common now, some older vehicles still have a separate ICM. This module triggers the ignition coils. A bad ICM will result in no spark.
* Power/Ground Issues: A poor connection or break in the main power supply or ground wires to the PCM, ignition system, and fuel injectors will prevent them from working. Check the battery terminals, fuses, and fusible links for corrosion and damage. Look for any broken or corroded wiring harnesses, particularly near the engine.
* Ignition Switch: A faulty ignition switch might not be providing the necessary power to the systems.
* Fuel Pump Relay: Although injectors aren't opening, a failed fuel pump relay can prevent power to the PCM leading to no spark or injection.
* Main Relay: A failed main relay could cut power to many systems, including the PCM.
Troubleshooting Steps (in order of likelihood and ease):
1. Check for obvious power/ground issues: Inspect battery terminals, fuses (particularly those related to ignition and fuel injection), and fusible links. Look for any obvious corrosion or damage to wiring.
2. Check the crankshaft position sensor: This is the most likely culprit. Inspect the sensor for damage and test its signal using a multimeter or an OBDII scanner (if equipped and able to read data from this sensor).
3. Check the camshaft position sensor (if applicable): Similar inspection and testing as the CKP.
4. Verify fuel pump operation: Even though injectors aren't firing, listen for the fuel pump priming when the key is turned to the "on" position but not started. If you don't hear it, investigate the fuel pump relay.
5. Use a code reader/scanner: If your 1991 Stealth has OBD-I capability (which it might not, depending on the trim), a scan tool can provide diagnostic trouble codes (DTCs) that pinpoint the issue. More sophisticated scan tools could even provide data stream to check sensor voltages.
6. Check ignition coil voltage: With a test light or multimeter, verify the ignition coil is receiving power.
7. Inspect the PCM/ECM: While you might not be able to test it easily, visual inspection for damage might give you some clues. If other checks fail this should be considered.
Important Note: Working on automotive electrical systems can be dangerous. If you're not comfortable working with car electronics, it's best to take your Stealth to a qualified mechanic. They have the diagnostic equipment and expertise to accurately identify and resolve the problem.
