1. Check the Obvious:
* Fuel Level: This is the most likely cause. Seriously, get some gas! Even if the gauge is faulty, it's possible you're actually out of fuel. Add at least a gallon and try starting it.
2. Fuel System Issues (If adding gas doesn't work):
* Fuel Pump: A faulty fuel pump can't deliver fuel to the engine, even if there's gas in the tank. You might hear a humming sound from the fuel pump when you turn the key to the "on" position (but not cranking). Lack of a hum suggests a possible problem. A mechanic can test the fuel pump.
* Fuel Filter: A clogged fuel filter restricts fuel flow. This is a relatively inexpensive and easy part to replace.
* Fuel Lines: A leak or blockage in the fuel lines can prevent fuel from reaching the engine. Inspect the lines visually for damage or leaks.
* Fuel Injectors: Faulty injectors might not be spraying fuel properly. This is more complex to diagnose and requires specialized tools.
3. Electrical Issues (If adding gas doesn't work):
* Fuel Gauge Sender Unit: The fuel gauge itself might be faulty. However, a faulty sender usually provides a reading (even an inaccurate one), rather than simply showing empty. The sender is located in the fuel tank. If the gauge *always* reads empty, this might not be the primary problem but still a possibility.
* Battery/Electrical System: A weak battery or problems with the car's electrical system can prevent the engine from cranking, even if there's plenty of fuel. Check the battery terminals for corrosion and clean them if needed. Test the battery voltage with a multimeter.
* Ignition Switch: A faulty ignition switch can prevent power from reaching the fuel pump or other essential components.
* Other Electrical Components: Wiring issues, relays, fuses related to the fuel system could cause this.
4. Immobilizer System (less likely, but possible):
* Some 1999 Wranglers might have an immobilizer system. A problem with the key or the immobilizer system could prevent the engine from starting.
Troubleshooting Steps:
1. Add gas: The simplest and most likely solution.
2. Listen for the fuel pump: Turn the key to "on" (not start) and listen near the fuel tank for a brief humming sound.
3. Check fuses: Check the fuses related to the fuel system in the fuse box (consult your owner's manual).
4. Visual inspection: Look for any obvious fuel leaks or damage to the fuel lines.
5. Battery voltage test: Use a multimeter to check the battery voltage.
When to Call a Mechanic:
If adding gas doesn't solve the problem, and you're not comfortable working on your car's fuel system, you should take it to a qualified mechanic. Working with fuel systems involves flammable liquids and requires proper safety precautions. Improper handling can be dangerous.
