1. Fuel System:
* Empty Tank: The most obvious! Check your fuel gauge.
* Fuel Pump: Listen carefully near the fuel tank while someone turns the ignition key. You should hear a brief humming sound from the fuel pump. If not, the pump might be faulty or the fuel pump relay is bad.
* Fuel Filter: A clogged fuel filter can restrict fuel flow. This is a relatively inexpensive part to replace.
* Fuel Injectors: These could be clogged or failing. This is more complex to diagnose and requires specialized tools or a mechanic.
* Fuel Pressure: A pressure gauge is needed to check if the fuel pressure is adequate. This requires a mechanic or the right tools.
2. Ignition System:
* Spark Plugs & Wires: Check the spark plugs for fouling (black, wet, or oily) or damage. Inspect the spark plug wires for cracks or damage. A simple way to check for spark (with caution!) is to remove a spark plug, ground it to the engine block, and have someone crank the engine. You should see a strong spark.
* Distributor Cap & Rotor: Inspect these components for cracks, corrosion, or worn contacts. Dirt or moisture can also cause problems.
* Ignition Coil: This part provides the high voltage for the spark plugs. A faulty coil will prevent starting.
* Ignition Control Module (ICM): This is a common failure point in older vehicles. It's a relatively inexpensive part to replace.
3. Battery & Charging System:
* Battery Voltage: Check the battery voltage with a multimeter. It should be around 12.6 volts when not cranking. If it's low, charge it or replace it.
* Battery Terminals: Clean the battery terminals and cables to ensure good electrical connection. Corrosion can significantly impede starting.
* Alternator: While not directly related to starting, a faulty alternator can prevent the battery from charging, leaving you stranded after a few attempts to start.
4. Starter Motor:
* Starter Solenoid: This is the electromagnet that engages the starter motor. A clicking sound when you turn the key often indicates a bad solenoid.
* Starter Motor: A failing starter motor might crank slowly or not at all.
5. Other Possibilities:
* Crank Position Sensor (CPS): This sensor tells the computer the position of the crankshaft. A bad CPS will prevent starting.
* Throttle Position Sensor (TPS): While less likely to completely prevent starting, a faulty TPS can affect the starting process, especially if it's sending incorrect signals.
* Computer Issues: In rare cases, a faulty computer or related module could be to blame.
Troubleshooting Steps:
1. Start with the easy checks: Battery voltage, fuel level, and obvious visual inspections (wires, connectors).
2. Listen carefully: Pay attention to sounds during cranking (clicking, grinding, humming).
3. Check spark: (safely!) Ensure spark plugs are firing.
4. Check for codes: If your Astro has a diagnostic port (OBD I), you may be able to retrieve diagnostic trouble codes. This would require a scanner.
If you're not comfortable working on your vehicle yourself, take it to a mechanic. The more information you can give them (sounds, symptoms, etc.), the easier it will be for them to diagnose the problem. Mentioning that it cranks but doesn't start is key information.
