* Carburetor Issues: This is the most likely culprit. The carburetor might be:
* Clogged jets: Dirt or debris can clog the jets responsible for fuel delivery at higher throttle positions. This is common with older vehicles.
* Faulty accelerator pump: The accelerator pump squirts fuel into the engine when you press the gas pedal. If it's weak or malfunctioning, the engine won't get enough fuel under acceleration.
* Incorrect carburetor adjustment: The carburetor needs to be properly adjusted for air/fuel mixture. An improperly adjusted carburetor can starve the engine of fuel under load.
* Stuck choke: A partially engaged choke can restrict airflow and fuel delivery.
* Diaphragm issues: Various diaphragms within the carburetor can fail, impacting fuel flow.
* Fuel Pump Issues: Though less likely given the idling behavior, a weak fuel pump might deliver enough fuel at idle but struggle to keep up when the engine demands more fuel under acceleration. Check fuel pressure.
* Fuel Filter: A clogged fuel filter will restrict fuel flow, manifesting similarly to a weak fuel pump.
* Ignition Timing: While you replaced ignition components, the timing itself could be off. Retarded timing (too much advance) can cause an engine to die under load. It's crucial this is checked.
Troubleshooting Steps:
1. Fuel Pressure Test: This is the most important first step. You'll need a fuel pressure gauge to measure fuel pressure at idle and when revving the engine. Low pressure under load points to a fuel pump or filter issue.
2. Carburetor Inspection: Carefully inspect the carburetor for any signs of clogging, damage, or incorrect adjustments. If you're not familiar with carburetors, take it to a mechanic. A rebuild kit might be necessary.
3. Ignition Timing Check: Have a mechanic check the ignition timing. Improper timing can cause this symptom.
4. Fuel Filter Replacement: While relatively inexpensive, replacing the fuel filter is a quick and easy preventative measure.
5. Vacuum Lines (Double Check): Even though you checked for vacuum leaks, double-check all vacuum lines connected to the carburetor and other emission systems, paying close attention to those influencing fuel delivery and mixture.
Recommendation: Unless you have significant experience working on carburetors, taking your Jeep to a mechanic specializing in older vehicles is recommended. They can diagnose the specific problem accurately and perform the necessary repairs efficiently. Describing the symptoms precisely ("dies when accelerating, idles fine") will help them troubleshoot effectively.
