* Crankshaft Position Sensor (CKP): This sensor tells the computer where the crankshaft is in its rotation. A faulty CKP sensor can cause the engine to start briefly and then die because the computer loses information about the engine's position. This is a very common cause of this type of starting problem.
* Cam Position Sensor (CMP): Similar to the CKP, a malfunctioning CMP sensor can disrupt the timing of the engine's ignition and fuel injection.
* Ignition System: Check the ignition coil, ignition module (if applicable), and spark plugs/wires. A weak spark or intermittent signal can cause the engine to cut out shortly after starting.
* Mass Air Flow (MAF) Sensor: A malfunctioning MAF sensor can provide inaccurate information to the engine computer, leading to improper fuel mixture and stalling.
* Throttle Position Sensor (TPS): An inaccurate reading from the TPS can cause the engine to idle poorly or stall.
* Computer Issues: Though less likely, a problem with the engine control module (ECM) itself could be at fault.
Why a jumped timing belt is less likely (but still possible): While a jumped timing belt *could* cause this symptom, it usually results in the engine not starting at all, or making a loud knocking sound if it does start. The fact that it runs for a second suggests the timing is probably somewhat close, but it's not entirely out of the question, especially if the belt is worn or damaged.
Troubleshooting Steps:
1. Check for error codes: Use an OBD-I scanner (appropriate for your 1990 model year) to see if any diagnostic trouble codes (DTCs) are stored in the computer. These codes can give you valuable clues.
2. Visual Inspection: Carefully examine the timing belt (if you're comfortable doing so) for wear, cracks, or signs of slippage.
3. Start with simpler checks: Before getting into timing belt work, test the CKP and CMP sensors (easy to access, relatively inexpensive). Check the ignition system and MAF/TPS sensors as well. These are easier checks and often resolve the issue.
4. Fuel Pressure Test: Even though you changed parts, a fuel pressure test can confirm whether you're getting sufficient fuel pressure.
If you're not comfortable working on your car's electrical system or internal components, it's best to take it to a mechanic for diagnosis. Attempting to work on the timing belt without proper experience can cause serious engine damage.
