2019 BMW M850i xDrive Fuel Tank Replacement Cost

The fuel tank is filled with fuel through the fill spout. The fill spout connects to the fuel tank filler neck, which will be equipped with a check valve or release valve, to allow the fuel going into the tank to replace air inside the tank. When the tank is full, and no air remains, the pressure signals the fuel station pump to stop sending fuel. Once fuel is inside the tank, it will adjust the mechanical float that reads fuel level, and be sucked from the tank on demand by the fuel pump.

The check engine light will illuminate any time there is a failed EVAP system test. This will be indicated by the various on-board diagnostics trouble codes that are stored in the vehicle's memory. Also, in some models, there may be a popping sound accompanying the check engine light, as the leak detection pump continuously attempts to pressurize the fuel tank. A fuel tank leak may also cause difficulty starting the engine, a rough idle, and poor fuel mileage. When a fuel tank is simply corroded to the point of failure, the exterior tank condition rarely shows damage. The inside of the fuel tank will be rusted or corroded, and rust flakes or other debris may be floating in the fuel.

A vehicle with a bad fuel tank should not be driven. The corrosion, debris, and rust inside the fuel tank will be further flushed into the fuel delivery system. The vehicle should not be started until the fuel is filtered, and the fuel tank and filter are replaced. Get this fixed by a RepairPal Certified Shop