1. Fuel System Issues:
* No Fuel Pressure: This is a very common reason. Check the fuel pump by listening for the whirring sound when you turn the key to the "on" position (before cranking). If you don't hear it, the pump may be failing. A fuel pressure gauge test is definitive.
* Clogged Fuel Filter: A restricted fuel filter can prevent sufficient fuel from reaching the engine. This is a relatively easy and inexpensive part to replace.
* Bad Fuel Injectors: They might be clogged, electrically faulty, or have low pressure. This requires more advanced diagnostics.
* Fuel Pump Relay: The relay might be bad and not sending power to the fuel pump. A simple swap with another relay (if possible) can quickly test this.
2. Ignition System Issues:
* Crankshaft Position Sensor (CKP Sensor): This sensor tells the computer the engine's rotational position. A faulty sensor prevents the computer from commanding fuel injection and ignition.
* Camshaft Position Sensor (CMP Sensor): Similar to the CKP sensor, but monitors the camshaft.
* Ignition Coil(s): These provide the high voltage needed for spark plugs. A weak or faulty coil will prevent ignition in one or more cylinders. A visual inspection for cracks or damage, followed by testing with a multimeter, is recommended.
* Spark Plugs and Wires: Worn or damaged spark plugs or wires can prevent a reliable spark. Inspect them for wear and tear.
* Ignition Control Module (ICM): This is the brain of the ignition system. A failing ICM can cause a no-start condition.
3. Other Possible Issues:
* Security System: If the van has an aftermarket or factory security system, it might be preventing the engine from starting.
* Low Compression: While less likely if the engine has been running fine recently, severely low compression in one or more cylinders will prevent starting. A compression test is necessary to diagnose this.
* Neutral Safety Switch: The vehicle won't start unless the transmission is in Park or Neutral. Verify this is in the correct position.
* Battery: While it cranks, a weak battery might not provide enough power to the ignition system or fuel pump. Test the battery voltage.
* Starter Relay: This relay controls power to the starter. A bad starter relay won't allow the starter to crank even if the battery is good.
Troubleshooting Steps:
1. Check the obvious: Battery voltage, fuel in the tank, transmission in park/neutral.
2. Listen for the fuel pump: Turn the key to "on" (but don't crank) and listen for the whirring sound of the fuel pump.
3. Check spark: With a spark tester, check for spark at the spark plugs. This requires disconnecting the wires to test individually.
4. Check codes: Use an OBD-II scanner to read any diagnostic trouble codes (DTCs) stored in the vehicle's computer. These codes can provide clues to the problem.
If you're not comfortable working on vehicles yourself, take it to a mechanic. Describing the symptoms ("cranks but doesn't start") will help them diagnose the problem efficiently. The steps above should provide valuable information for the mechanic as well.
