* Fuel Pump Issues: A failing fuel pump may be unable to maintain sufficient pressure to keep the engine running consistently. Heat can exacerbate this, causing it to fail intermittently. When the car sits, the pump cools down, allowing it to restart (temporarily). This is a very common cause of this type of problem.
* Clogged Fuel Filter: A severely clogged fuel filter restricts fuel flow, leading to similar symptoms as a failing fuel pump. The engine might run until the pressure drops too low, then stall. Again, sitting allows the remaining fuel to filter through the partially blocked filter enough for a restart.
* Fuel Pressure Regulator: A malfunctioning fuel pressure regulator can cause inconsistent fuel pressure, leading to stalling. Similar to the fuel pump, cooling down allows a temporary return to functionality.
* Crankshaft Position Sensor (CKP Sensor): This sensor tells the engine's computer where the crankshaft is in its rotation. A faulty CKP sensor can cause the engine to shut down unpredictably. While this doesn't directly relate to "out of gas," the symptoms might appear similar. The engine computer might shut down fuel delivery thinking there's a problem.
* Mass Airflow Sensor (MAF Sensor): This sensor measures the amount of air entering the engine. A faulty MAF sensor can cause a lean fuel condition (too much air, not enough fuel), leading to stalling. While not directly an "out of gas" scenario, the symptoms overlap.
* Ignition Switch/Wiring Issues: While less likely, a problem with the ignition switch or its wiring could intermittently cut power to the fuel pump or other crucial components.
* Fuel Tank Sender Unit: This is less likely to cause the immediate stalling but could contribute to the "out of gas" reading on the gauge. If the sender is faulty, it might give an incorrect fuel level reading, even if there's plenty of fuel.
Troubleshooting Steps (in order of likelihood and ease):
1. Check the Fuel Level: This is the first and easiest step. Make absolutely sure you actually *do* have fuel. A faulty gauge is possible.
2. Listen for the Fuel Pump: When you turn the ignition key to the "on" position (but don't start the engine), you should hear a brief humming sound from the fuel pump in the tank. If you don't hear it, the pump may be failing.
3. Check the Fuel Filter: This is relatively easy to access and replace. A dirty filter is a common cause of fuel delivery problems.
4. Check Fuel Pressure (if you have the tools): This requires a fuel pressure gauge and knowledge of how to safely connect it to your fuel system. This is a more advanced diagnostic step.
5. Scan the OBD-II Port (if applicable): If your Roadmaster is equipped with an OBD-II port, a scan tool can retrieve diagnostic trouble codes (DTCs) that might pinpoint the problem.
Important Safety Note: Working on a fuel system involves flammable materials. Take necessary precautions to avoid fire hazards. If you're not comfortable performing these checks yourself, take your Buick Roadmaster to a qualified mechanic for diagnosis and repair.
