Fuel System Problems:
* Empty or Low Fuel: Sounds obvious, but always check the fuel gauge.
* Fuel Pump Failure: The pump may be weak, failing to deliver enough fuel to the engine. Listen carefully near the fuel tank for the hum of the fuel pump when you turn the key to the "on" position (before cranking). No hum suggests a problem.
* Clogged Fuel Filter: A blocked filter restricts fuel flow.
* Bad Fuel Injectors: Injectors may be clogged, faulty, or not receiving the correct electrical signal.
* Fuel Pressure Regulator: A faulty regulator could be causing incorrect fuel pressure.
Ignition System Problems:
* Spark Plugs: Worn, fouled, or damaged spark plugs prevent proper ignition.
* Ignition Coil: The coil may be failing to provide sufficient voltage to the spark plugs. Multiple coils are possible depending on the engine.
* Distributor Cap and Rotor (if applicable): These components (present in some older Wranglers) can corrode and cause intermittent or complete spark failure. Less likely in a 2000 model, but still a possibility.
* Ignition Wires: Damaged or loose wires can disrupt the spark delivery.
* Crankshaft Position Sensor (CKP): This sensor tells the computer the engine's rotational position. A faulty CKP prevents proper ignition timing.
* Cam Position Sensor (CMP): Similar to the CKP, a faulty CMP can disrupt ignition timing.
* PCV Valve: A severely clogged PCV valve can cause a lean condition and prevent starting.
Other Potential Issues:
* Security System: A faulty alarm or immobilizer system can prevent starting.
* Battery Cables: Corroded or loose battery cables can reduce the electrical current needed for starting. Clean the terminals thoroughly.
* Alternator: While unlikely to prevent starting initially, a completely failed alternator could mean the battery won't have enough charge.
Troubleshooting Steps:
1. Check the obvious: Fuel level, battery cables, battery voltage.
2. Listen for the fuel pump: Listen for a hum near the fuel tank when the key is turned to the "on" position.
3. Check for spark: A simple spark tester can determine if spark plugs are receiving spark.
4. Check the engine codes: Use an OBD-II scanner to read any diagnostic trouble codes (DTCs) stored by the engine's computer. These codes can provide valuable clues.
If you're not comfortable working on your Jeep yourself, it's best to take it to a qualified mechanic for diagnosis and repair. Attempting repairs without proper knowledge could lead to further damage.
