Here's a breakdown of possible causes and troubleshooting steps:
* Faulty Fuel Gauge Sending Unit: This is the most likely problem. The sending unit needs to be replaced. This involves dropping the fuel tank (a significant job).
* Faulty Fuel Gauge Cluster: Less likely, but the gauge itself in the instrument cluster could be malfunctioning. This is usually diagnosed by testing the gauge with a multimeter after verifying the sending unit signal.
* Wiring Issues: A break or short in the wiring between the sending unit and the gauge could also cause an inaccurate reading. Inspect the wiring for damage.
* Bad Ground: A poor ground connection can affect the gauge's accuracy. Check the ground connection for the fuel gauge system.
What you should NOT do:
* Keep driving: Running your vehicle out of gas can damage the fuel pump.
What you SHOULD do:
1. Verify the tank is actually empty: Before jumping to conclusions, be absolutely sure there's no gas in the tank. Try adding a small amount of gas to see if the gauge moves. If it does, the problem is likely with the sending unit. If it does not move at all, it's more likely a gauge problem.
2. Check the Fuel Pump Relay: A faulty relay might prevent the fuel pump from operating even if the tank is full. This is a simpler check than dropping the fuel tank. Locate the fuel pump relay (your owner's manual should show its location) and try swapping it with a known good relay of the same amperage.
3. Consult a Repair Manual: A repair manual specific to your 2000 Chevy Express van will provide detailed diagrams and instructions for testing the sending unit, gauge, and wiring.
4. Professional Mechanic: Replacing the fuel gauge sending unit is a relatively complex repair that involves working with fuel, potentially hazardous fumes, and dropping the fuel tank. Unless you have significant automotive experience, it's best to have a qualified mechanic diagnose and repair the problem. This is especially true since you'll need to properly dispose of fuel during the repair process.
In short, while it *could* be a number of issues, the most probable cause is a failed fuel sending unit. Proceed cautiously and consider professional help.
