(MCT) -- Q: When I reach about a half tank of gas with my 2006 Hyundai Azera 3.8 engine, the gas gauge goes down to empty and the low fuel light comes on. Is there a sensor that controls the gauge or is there a problem with the fuel pump? If there is a sensor, can I replace it myself or should I take it to a mechanic?
A: Your Azera utilizes a fuel tank module consisting of the fuel pump and gas gauge sending unit. The sending unit contains a variable resistor and float lever. Differing fuel levels move the lever, resulting in greater electrical resistance with a low fuel level and less resistance when the tank is full. A faulty electrical connection is the cause of your gauge dropping to empty, because high resistance and bad connections go hand in hand. Since your symptom occurs only when fuel is at a certain level rather than at random times, it's safe to say the electrical fault is within the sending unit.
Combining both the sender and fuel pump unfortunately means one needs to replace the complete unit even though only one part is faulty. If your Azera has racked up 80,000 miles or more, the fuel pump is entering its twilight time, if that helps one stomach the $300-400 parts cost, plus installation. The fuel module is accessed by removing the back seat and then a thoughtfully convenient hatch in the floor. Book time for renewal is one hour. It's not a difficult job, but one needs to diligently follow published safety precautions/procedures because of fuel vapors entering the vehicle and liquid fuel directly beneath.