Fuel System:
* Dirty or clogged carburetor: This is the most probable cause in a carbureted CJ7. Dirt, debris, or varnish buildup can restrict fuel flow, especially at idle when the fuel mixture is delicate. Cleaning or rebuilding the carburetor is often the solution.
* Clogged fuel filter: A blocked filter restricts fuel flow, leading to stalling. Replacing the filter is inexpensive and should be done regularly.
* Fuel pump problems: A weak or failing fuel pump may not deliver enough fuel pressure, especially at idle when the engine demands less. Check the fuel pressure.
* Vacuum leaks: Leaks in the vacuum lines connected to the carburetor can disrupt the fuel/air mixture, causing stalling. Inspect all vacuum lines for cracks, holes, or loose connections.
* Bad fuel: Stale, contaminated fuel can cause problems. Consider draining and replacing the fuel.
Ignition System:
* Weak ignition coil: A failing coil won't provide enough spark to ignite the fuel consistently, especially at idle.
* Worn distributor cap and rotor: These components distribute the high-voltage spark to the spark plugs. Corrosion or wear can cause misfires and stalling.
* Worn or fouled spark plugs: Dirty or damaged spark plugs can prevent proper combustion. Inspect them for wear, fouling, or damage. Replace if necessary.
* Ignition timing: Incorrect timing can affect idle and cause stalling. A mechanic with a timing light can check and adjust it.
Other Potential Issues:
* Throttle linkage problems: A sticky or improperly adjusted throttle cable can prevent the engine from receiving enough air at idle.
* Choke problems: If your CJ7 has a manual choke, it might be sticking or not disengaging properly after warming up.
* PCV Valve: A plugged PCV (positive crankcase ventilation) valve can cause excessive crankcase pressure, disrupting the air-fuel mixture.
* Intake manifold gasket leak: A leak in the intake manifold gasket can cause a lean air-fuel mixture, resulting in stalling.
Troubleshooting Steps:
1. Start with the easy checks: Check the fuel filter and visually inspect the fuel lines for leaks.
2. Inspect the carburetor: Look for visible signs of dirt or damage. If you're comfortable, try cleaning it yourself, otherwise, take it to a mechanic.
3. Check the spark plugs: Examine them for wear, fouling, or damage. Replace if necessary.
4. Check the distributor cap and rotor: Look for corrosion or cracks. Replace if needed.
5. Listen for vacuum leaks: With the engine running, listen carefully for hissing sounds around the intake manifold and carburetor. Use a propane torch (carefully!) to check for vacuum leaks near the intake manifold (the flame will be sucked into a leak).
If you're not comfortable working on your carburetor or ignition system, it's best to take your Jeep to a mechanic specializing in older vehicles, especially Jeeps. They have the experience and tools to diagnose the problem accurately and efficiently. Providing more details about what happens when it stalls (e.g., does it sputter before stalling? Does the engine seem to lack power?) could help pinpoint the problem further.
