1. Fuel System Issues:
* Fuel Pump: The most common cause. The fuel pump might have failed, or its relay might be bad. Listen carefully while someone cranks the engine – you should hear a whirring sound from the fuel pump (usually near the fuel tank) for a second or two when the key is first turned to the "on" position (before cranking). If you don't hear it, the pump or its relay is suspect.
* Fuel Filter: A clogged fuel filter can restrict fuel flow, preventing the engine from starting. This is a relatively inexpensive and easy part to replace.
* Fuel Pressure: A low fuel pressure can also prevent starting. This requires a fuel pressure gauge to test.
* Fuel Injectors: Though less likely to suddenly fail, a problem with one or more injectors could prevent starting. This requires more advanced diagnostics.
2. Ignition System Issues:
* Distributor Cap and Rotor: Corrosion or wear in these components can interrupt the spark to the plugs. Inspect them for cracks, burning, or excessive wear.
* Spark Plugs and Wires: Worn, fouled, or loose spark plugs or wires can prevent a spark, or cause a weak spark. Check for cracks, corrosion, and proper connection.
* Ignition Coil: A faulty ignition coil won't deliver the necessary high voltage to the spark plugs.
* Ignition Control Module (ICM): This module controls the ignition system. Failure is possible, but less common.
* Crankshaft Position Sensor (CKP Sensor): This sensor tells the computer the engine's rotational position. A faulty sensor will prevent the engine from starting.
3. Other Potential Problems:
* Battery: Although it cranked, a weak battery might not provide enough power to start the engine, especially if the starter motor is drawing extra current. Check the battery voltage.
* Starter Motor: While it cranks, a failing starter motor might not provide enough power to turn the engine over fast enough to ignite the fuel/air mixture.
* Security System: If your van has an aftermarket or factory alarm or immobilizer system, it might be preventing the engine from starting. Check the system's status.
* Neutral Safety Switch: This switch prevents the engine from starting unless the transmission is in Park or Neutral. Make sure the gear selector is in the correct position.
* PCM (Powertrain Control Module): While less likely, a faulty PCM can cause starting problems. This typically requires professional diagnostics.
Troubleshooting Steps:
1. Check the basics: Battery voltage, fuel level, and ensure the gear selector is in Park or Neutral.
2. Listen for the fuel pump: Turn the key to the "on" position (without cranking) and listen for the fuel pump whirring.
3. Inspect the spark plugs and wires: Check for any obvious signs of damage or fouling.
4. Check the distributor cap and rotor: Inspect for cracks, burning, or excessive wear.
5. If you have basic mechanical skills: Attempt to check fuel pressure (requires a fuel pressure gauge).
If you're not comfortable working on your vehicle yourself, take it to a qualified mechanic for diagnosis and repair. Providing more information (like any warning lights that were on, any unusual sounds, etc.) will help in narrowing down the possibilities.
