* Transmission Issues: A failing torque converter, low transmission fluid, problems with the transmission's internal components, or a malfunctioning shift linkage could all cause the van to die when put into gear. The engine might not be able to overcome the resistance of the transmission trying to move the vehicle.
* Fuel Delivery Problem: The fuel pump might be weak and only able to supply enough fuel at idle. Once under load (in gear), it can't keep up with the demand. A clogged fuel filter or issues with the fuel injectors could also contribute.
* Ignition System Problems: A weak ignition coil, failing distributor cap or rotor, or worn spark plug wires might deliver enough spark at idle but fail under the increased demand of driving.
* Vacuum Leaks: A significant vacuum leak in the intake system can cause the engine to stall under load.
* Neutral Safety Switch: This switch prevents the engine from starting unless the transmission is in park or neutral. A faulty switch might be preventing the engine from getting the proper signal when in gear.
* Computer/Sensor Problems: A problem with the engine control module (ECM) or related sensors (like the crankshaft position sensor or throttle position sensor) could be causing the engine to shut down when put under load.
Troubleshooting Steps (in order of easiest/cheapest to most involved):
1. Check Transmission Fluid: Low or dirty transmission fluid is a very common cause. Check the fluid level and condition. If it's low, add fluid (the correct type!), but a low fluid level is usually a symptom of a bigger problem.
2. Check Engine Light: Is the check engine light illuminated? If so, have the codes read at an auto parts store (many offer free diagnostic scans) to identify potential problems.
3. Listen for Unusual Noises: When attempting to put the van into gear, listen carefully for unusual noises from the transmission.
4. Check Fuel Pressure: This requires a fuel pressure gauge and may require some mechanical knowledge. Low fuel pressure indicates a fuel pump or fuel filter issue.
5. Inspect Vacuum Lines: Carefully inspect all vacuum lines for cracks or leaks.
6. Test the Neutral Safety Switch: This involves testing the switch with a multimeter to ensure it is sending the correct signals to the engine.
Important Note: Without a proper diagnosis, it's difficult to pinpoint the exact cause. If you're not comfortable working on vehicles, taking it to a qualified mechanic is the safest and most efficient way to resolve the issue. Trying to guess the problem and replace parts could end up being costly and time-consuming.
