Most Likely Culprits:
* Faulty Fuel Level Sensor: This sensor tells the gauge how much fuel is in the tank. If it's malfunctioning and providing inaccurate readings *around* the half-tank point, it might be causing a secondary problem. While an inaccurate gauge is annoying, it's not directly causing the engine to stall. However, some fuel systems have a safety mechanism that shuts off the fuel pump based on the fuel level sensor's input. A faulty sensor could be giving a false "low fuel" signal around half a tank.
* Debris in the Fuel Tank: Sediment or rust in the tank can clog the fuel pickup, especially when the fuel level is low enough that the pickup is drawing from the bottom of the tank near the sediment. When the fuel level is around half a tank, the angle of the pickup might change, allowing debris to partially or fully block fuel flow.
* Fuel Pump (less likely at half tank): While a failing fuel pump usually causes issues across the fuel range, its performance can degrade more noticeably when the tank is lower, as it has to work harder to pull fuel up. It's less likely to be *only* a problem at the half-tank mark.
* Fuel Filter Clogging: A clogged fuel filter restricts fuel flow. Again, more likely to show problems consistently, not just around half a tank.
* Bad Fuel Pump Relay: This is less likely, but a relay that's failing under specific conditions (like the heat from the motor causing it to overheat at a certain tank level) is possible.
Troubleshooting Steps:
1. Check the Fuel Gauge Accuracy: Does the gauge actually move smoothly and consistently, or does it jump or stick around the half-tank mark?
2. Clean the Fuel Tank: If the gauge seems relatively accurate, the most direct solution would be a fuel tank cleaning and inspection. This often requires dropping the tank, which is a more involved job. A fuel system cleaner added to the tank might help, but a thorough cleaning might be necessary.
3. Check the Fuel Filter: Replace the fuel filter. It's a relatively inexpensive and easy replacement that is often overlooked.
4. Inspect the Fuel Pump Relay: Check for corrosion or damage. You may need to use a multimeter to test its functionality. This usually involves locating the relay based on your vehicle's wiring diagram.
5. Fuel Pump Pressure Test: This is the most definitive way to rule out a fuel pump issue. You'll need a fuel pressure gauge and likely some adapters to attach it to your fuel system. Compare the reading to the factory specification for your engine.
Important Note: If you're not comfortable working on your car's fuel system yourself, take it to a qualified mechanic. Working with fuel is dangerous, and improper handling could lead to fire or injury. A mechanic will have the tools and expertise to diagnose the problem accurately and safely.
