1. Battery Issues:
* Dead Battery: This is the most frequent cause. Test the battery voltage with a multimeter. It should read around 12.6 volts when fully charged. Less than that indicates a weak or dead battery. Jump starting it can confirm this.
* Loose or Corroded Battery Terminals: Clean the terminals with a wire brush and baking soda solution. Make sure they are securely fastened.
* Faulty Battery Cables: Check for breaks or corrosion in the cables connecting the battery to the starter and the rest of the electrical system.
2. Starting System Problems:
* Faulty Starter: The starter motor may be failing. This requires testing with a multimeter or a mechanic's assistance. A clicking sound when you turn the key is often a sign of a failing starter or a low battery.
* Bad Starter Solenoid: This is the relay between the battery and the starter. A clicking sound is also common here.
* Poor Connections in the Starting Circuit: Check all the connections in the starting system for corrosion or looseness.
3. Ignition System Problems:
* Faulty Ignition Switch: This switches the power to the rest of the system. If the key doesn't turn smoothly or there's no power to anything, this is a possibility.
* Ignition Coil: This provides the high voltage spark to ignite the fuel. A faulty coil can prevent the engine from starting.
* Spark Plugs/Wires: Worn or fouled spark plugs or damaged wires can prevent a spark.
4. Fuel System Problems:
* Empty Fuel Tank: Seems obvious, but it's worth checking!
* Fuel Pump Failure: The fuel pump delivers fuel to the engine. A faulty pump may not provide fuel pressure. You might hear a humming sound when you turn the key if the pump is trying to work but failing.
* Clogged Fuel Filter: A dirty filter can restrict fuel flow.
* Fuel Injectors: Problems with the injectors can prevent fuel from being sprayed into the cylinders.
5. Other Possibilities:
* Security System Issues: If the van has an aftermarket alarm or immobilizer system, it might be preventing the engine from starting.
* Neutral Safety Switch: This switch prevents the engine from starting unless the transmission is in Park or Neutral.
* Sensor Problems: Various sensors (crankshaft position sensor, camshaft position sensor, etc.) can prevent the engine from starting if faulty.
Troubleshooting Steps:
1. Check the obvious: Battery, fuel level.
2. Listen for sounds: Clicking from the starter, humming from the fuel pump.
3. Visual inspection: Check for loose or corroded connections.
4. Use a multimeter: Test battery voltage, starter current draw.
5. Consult a repair manual: A Haynes or Chilton manual specific to the 1995 Chevy Astro will be very helpful.
If you're not comfortable working on cars yourself, it's best to take it to a mechanic for diagnosis and repair. Trying to fix things without proper knowledge can lead to further damage. Providing more information, like any sounds the van makes when you turn the key, will help narrow down the possibilities.
